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<title>Installing GCC: Configuration</title>

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<a class="index-entry-id" id="index-Configuration"></a>
<a class="index-entry-id" id="index-Installing-GCC_003a-Configuration"></a>

<p>Like most GNU software, GCC must be configured before it can be built.
This document describes the recommended configuration procedure
for both native and cross targets.
</p>
<p>We use <var class="var">srcdir</var> to refer to the toplevel source directory for
GCC; we use <var class="var">objdir</var> to refer to the toplevel build/object directory.
</p>
<p>If you obtained the sources by cloning the repository, <var class="var">srcdir</var>
must refer to the top <samp class="file">gcc</samp> directory, the one where the
<samp class="file">MAINTAINERS</samp> file can be found, and not its <samp class="file">gcc</samp>
subdirectory, otherwise the build will fail.
</p>
<p>If either <var class="var">srcdir</var> or <var class="var">objdir</var> is located on an automounted NFS
file system, the shell&rsquo;s built-in <code class="command">pwd</code> command will return
temporary pathnames.  Using these can lead to various sorts of build
problems.  To avoid this issue, set the <code class="env">PWDCMD</code> environment
variable to an automounter-aware <code class="command">pwd</code> command, e.g.,
<code class="command">pawd</code> or &lsquo;<samp class="samp">amq -w</samp>&rsquo;, during the configuration and build
phases.
</p>
<p>First, we <strong class="strong">highly</strong> recommend that GCC be built into a
separate directory from the sources which does <strong class="strong">not</strong> reside
within the source tree.  This is how we generally build GCC; building
where <var class="var">srcdir</var> == <var class="var">objdir</var> should still work, but doesn&rsquo;t
get extensive testing; building where <var class="var">objdir</var> is a subdirectory
of <var class="var">srcdir</var> is unsupported.
</p>
<p>If you have previously built GCC in the same directory for a
different target machine, do &lsquo;<samp class="samp">make distclean</samp>&rsquo; to delete all files
that might be invalid.  One of the files this deletes is <samp class="file">Makefile</samp>;
if &lsquo;<samp class="samp">make distclean</samp>&rsquo; complains that <samp class="file">Makefile</samp> does not exist
or issues a message like &ldquo;don&rsquo;t know how to make distclean&rdquo; it probably
means that the directory is already suitably clean.  However, with the
recommended method of building in a separate <var class="var">objdir</var>, you should
simply use a different <var class="var">objdir</var> for each target.
</p>
<p>Second, when configuring a native system, either <code class="command">cc</code> or
<code class="command">gcc</code> must be in your path or you must set <code class="env">CC</code> in
your environment before running configure.  Otherwise the configuration
scripts may fail.
</p>

<p>To configure GCC:
</p>
<div class="example smallexample">
<pre class="example-preformatted">% mkdir <var class="var">objdir</var>
% cd <var class="var">objdir</var>
% <var class="var">srcdir</var>/configure [<var class="var">options</var>] [<var class="var">target</var>]
</pre></div>

<h3 class="heading" id="Distributor-options"><span>Distributor options<a class="copiable-link" href="#Distributor-options"> &para;</a></span></h3>

<p>If you will be distributing binary versions of GCC, with modifications
to the source code, you should use the options described in this
section to make clear that your version contains modifications.
</p>
<dl class="table">
<dt><code class="code">--with-pkgversion=<var class="var">version</var></code></dt>
<dd><p>Specify a string that identifies your package.  You may wish
to include a build number or build date.  This version string will be
included in the output of <code class="command">gcc --version</code>.  This suffix does
not replace the default version string, only the &lsquo;<samp class="samp">GCC</samp>&rsquo; part.
</p>
<p>The default value is &lsquo;<samp class="samp">GCC</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">--with-bugurl=<var class="var">url</var></code></dt>
<dd><p>Specify the URL that users should visit if they wish to report a bug.
You are of course welcome to forward bugs reported to you to the FSF,
if you determine that they are not bugs in your modifications.
</p>
<p>The default value refers to the FSF&rsquo;s GCC bug tracker.
</p>
</dd>
<dt><code class="code">--with-documentation-root-url=<var class="var">url</var></code></dt>
<dd><p>Specify the URL root that contains GCC option documentation.  The <var class="var">url</var>
should end with a <code class="code">/</code> character.
</p>
<p>The default value is <a class="uref" href="https://gcc.gnu.org/onlinedocs/">https://gcc.gnu.org/onlinedocs/</a>.
</p>
</dd>
<dt><code class="code">--with-changes-root-url=<var class="var">url</var></code></dt>
<dd><p>Specify the URL root that contains information about changes in GCC
releases like <code class="code">gcc-<var class="var">version</var>/changes.html</code>.
The <var class="var">url</var> should end with a <code class="code">/</code> character.
</p>
<p>The default value is <a class="uref" href="https://gcc.gnu.org/">https://gcc.gnu.org/</a>.
</p>
</dd>
</dl>

<h3 class="heading" id="Host_002c-Build-and-Target-specification"><span>Host, Build and Target specification<a class="copiable-link" href="#Host_002c-Build-and-Target-specification"> &para;</a></span></h3>

<p>Specify the host, build and target machine configurations.  You do this
when you run the <samp class="file">configure</samp> script.
</p>
<p>The <em class="dfn">build</em> machine is the system which you are using, the
<em class="dfn">host</em> machine is the system where you want to run the resulting
compiler (normally the build machine), and the <em class="dfn">target</em> machine is
the system for which you want the compiler to generate code.
</p>
<p>If you are building a compiler to produce code for the machine it runs
on (a native compiler), you normally do not need to specify any operands
to <samp class="file">configure</samp>; it will try to guess the type of machine you are on
and use that as the build, host and target machines.  So you don&rsquo;t need
to specify a configuration when building a native compiler unless
<samp class="file">configure</samp> cannot figure out what your configuration is or guesses
wrong.
</p>
<p>In those cases, specify the build machine&rsquo;s <em class="dfn">configuration name</em>
with the <samp class="option">--host</samp> option; the host and target will default to be
the same as the host machine.
</p>
<p>Here is an example:
</p>
<div class="example smallexample">
<pre class="example-preformatted">./configure --host=x86_64-pc-linux-gnu
</pre></div>

<p>A configuration name may be canonical or it may be more or less
abbreviated (<samp class="file">config.sub</samp> script produces canonical versions).
</p>
<p>A canonical configuration name has three parts, separated by dashes.
It looks like this: &lsquo;<samp class="samp"><var class="var">cpu</var>-<var class="var">company</var>-<var class="var">system</var></samp>&rsquo;.
</p>
<p>Here are the possible CPU types:
</p>
<blockquote class="quotation">
<p>aarch64, aarch64_be, alpha, alpha64, amdgcn, arc, arceb, arm, armeb, avr, bfin,
bpf, cris, csky, epiphany, fido, fr30, frv, ft32, h8300, hppa, hppa2.0,
hppa64, i486, i686, ia64, iq2000, lm32, loongarch64, m32c, m32r, m32rle, m68k,
mcore, microblaze, microblazeel, mips, mips64, mips64el, mips64octeon,
mips64orion, mips64vr, mipsel, mipsisa32, mipsisa32r2, mipsisa64, mipsisa64r2,
mipsisa64r2el, mipsisa64sb1, mipsisa64sr71k, mipstx39, mmix, mn10300, moxie,
msp430, nds32be, nds32le, nios2, nvptx, or1k, pdp11, powerpc, powerpc64,
powerpc64le, powerpcle, pru, riscv32, riscv32be, riscv64, riscv64be, rl78, rx,
s390, s390x, sh, shle, sparc, sparc64, tic6x, v850,
v850e, v850e1, vax, visium, x86_64, xstormy16, xtensa
</p></blockquote>

<p>Here is a list of system types:
</p>
<blockquote class="quotation">
<p>aix<var class="var">version</var>, amdhsa, aout, cygwin, darwin<var class="var">version</var>,
eabi, eabialtivec, eabisim, eabisimaltivec, elf, elf32,
elfbare, elfoabi, freebsd<var class="var">version</var>, gnu, hpux, hpux<var class="var">version</var>,
kfreebsd-gnu, kopensolaris-gnu, linux-androideabi, linux-gnu,
linux-gnu_altivec, linux-musl, linux-uclibc, lynxos, mingw32, mingw32crt,
mmixware, msdosdjgpp, netbsd, netbsdelf<var class="var">version</var>, nto-qnx, openbsd,
rtems, solaris<var class="var">version</var>, symbianelf, tpf, uclinux, uclinux_eabi, vms,
vxworks, vxworksae, vxworksmils
</p></blockquote>

<h3 class="heading" id="Options-specification"><span>Options specification<a class="copiable-link" href="#Options-specification"> &para;</a></span></h3>

<p>Use <var class="var">options</var> to override several configure time options for
GCC.  A list of supported <var class="var">options</var> follows; &lsquo;<samp class="samp">configure
--help</samp>&rsquo; may list other options, but those not listed below may not
work and should not normally be used.
</p>
<p>Note that each <samp class="option">--enable</samp> option has a corresponding
<samp class="option">--disable</samp> option and that each <samp class="option">--with</samp> option has a
corresponding <samp class="option">--without</samp> option.
</p>
<dl class="table">
<dt><code class="code">--prefix=<var class="var">dirname</var></code></dt>
<dd><p>Specify the toplevel installation
directory.  This is the recommended way to install the tools into a directory
other than the default.  The toplevel installation directory defaults to
<samp class="file">/usr/local</samp>.
</p>
<p>We <strong class="strong">highly</strong> recommend against <var class="var">dirname</var> being the same or a
subdirectory of <var class="var">objdir</var> or vice versa.  If specifying a directory
beneath a user&rsquo;s home directory tree, some shells will not expand
<var class="var">dirname</var> correctly if it contains the &lsquo;<samp class="samp">~</samp>&rsquo; metacharacter; use
<code class="env">$HOME</code> instead.
</p>
<p>The following standard <code class="command">autoconf</code> options are supported.  Normally you
should not need to use these options.
</p><dl class="table">
<dt><code class="code">--exec-prefix=<var class="var">dirname</var></code></dt>
<dd><p>Specify the toplevel installation directory for architecture-dependent
files.  The default is <samp class="file"><var class="var">prefix</var></samp>.
</p>
</dd>
<dt><code class="code">--bindir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for the executables called by users
(such as <code class="command">gcc</code> and <code class="command">g++</code>).  The default is
<samp class="file"><var class="var">exec-prefix</var>/bin</samp>.
</p>
</dd>
<dt><code class="code">--libdir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for object code libraries and
internal data files of GCC.  The default is <samp class="file"><var class="var">exec-prefix</var>/lib</samp>.
</p>
</dd>
<dt><code class="code">--libexecdir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for internal executables of GCC.
The default is <samp class="file"><var class="var">exec-prefix</var>/libexec</samp>.
</p>
</dd>
<dt><code class="code">--with-slibdir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for the shared libgcc library.  The
default is <samp class="file"><var class="var">libdir</var></samp>.
</p>
</dd>
<dt><code class="code">--datarootdir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the root of the directory tree for read-only architecture-independent
data files referenced by GCC.  The default is <samp class="file"><var class="var">prefix</var>/share</samp>.
</p>
</dd>
<dt><code class="code">--infodir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for documentation in info format.
The default is <samp class="file"><var class="var">datarootdir</var>/info</samp>.
</p>
</dd>
<dt><code class="code">--datadir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for some architecture-independent
data files referenced by GCC.  The default is <samp class="file"><var class="var">datarootdir</var></samp>.
</p>
</dd>
<dt><code class="code">--docdir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for documentation files (other
than Info) for GCC.  The default is <samp class="file"><var class="var">datarootdir</var>/doc</samp>.
</p>
</dd>
<dt><code class="code">--htmldir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for HTML documentation files.
The default is <samp class="file"><var class="var">docdir</var></samp>.
</p>
</dd>
<dt><code class="code">--pdfdir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for PDF documentation files.
The default is <samp class="file"><var class="var">docdir</var></samp>.
</p>
</dd>
<dt><code class="code">--mandir=<var class="var">dirname</var></code></dt>
<dd><p>Specify the installation directory for manual pages.  The default is
<samp class="file"><var class="var">datarootdir</var>/man</samp>.  (Note that the manual pages are only extracts
from the full GCC manuals, which are provided in Texinfo format.  The manpages
are derived by an automatic conversion process from parts of the full
manual.)
</p>
</dd>
<dt><code class="code">--with-gxx-include-dir=<var class="var">dirname</var></code></dt>
<dd><p>Specify
the installation directory for G++ header files.  The default depends
on other configuration options, and differs between cross and native
configurations.
</p>
</dd>
<dt><code class="code">--with-specs=<var class="var">specs</var></code></dt>
<dd><p>Specify additional command line driver SPECS.
This can be useful if you need to turn on a non-standard feature by
default without modifying the compiler&rsquo;s source code, for instance
<samp class="option">--with-specs=%{!fcommon:%{!fno-common:-fno-common}}</samp>.
See &ldquo;Spec Files&rdquo; in the main manual
</p>
</dd>
</dl>

</dd>
<dt><code class="code">--program-prefix=<var class="var">prefix</var></code></dt>
<dd><p>GCC supports some transformations of the names of its programs when
installing them.  This option prepends <var class="var">prefix</var> to the names of
programs to install in <var class="var">bindir</var> (see above).  For example, specifying
<samp class="option">--program-prefix=foo-</samp> would result in &lsquo;<samp class="samp">gcc</samp>&rsquo;
being installed as <samp class="file">/usr/local/bin/foo-gcc</samp>.
</p>
</dd>
<dt><code class="code">--program-suffix=<var class="var">suffix</var></code></dt>
<dd><p>Appends <var class="var">suffix</var> to the names of programs to install in <var class="var">bindir</var>
(see above).  For example, specifying <samp class="option">--program-suffix=-3.1</samp>
would result in &lsquo;<samp class="samp">gcc</samp>&rsquo; being installed as
<samp class="file">/usr/local/bin/gcc-3.1</samp>.
</p>
</dd>
<dt><code class="code">--program-transform-name=<var class="var">pattern</var></code></dt>
<dd><p>Applies the &lsquo;<samp class="samp">sed</samp>&rsquo; script <var class="var">pattern</var> to be applied to the names
of programs to install in <var class="var">bindir</var> (see above).  <var class="var">pattern</var> has to
consist of one or more basic &lsquo;<samp class="samp">sed</samp>&rsquo; editing commands, separated by
semicolons.  For example, if you want the &lsquo;<samp class="samp">gcc</samp>&rsquo; program name to be
transformed to the installed program <samp class="file">/usr/local/bin/myowngcc</samp> and
the &lsquo;<samp class="samp">g++</samp>&rsquo; program name to be transformed to
<samp class="file">/usr/local/bin/gspecial++</samp> without changing other program names,
you could use the pattern
<samp class="option">--program-transform-name='s/^gcc$/myowngcc/; s/^g++$/gspecial++/'</samp>
to achieve this effect.
</p>
<p>All three options can be combined and used together, resulting in more
complex conversion patterns.  As a basic rule, <var class="var">prefix</var> (and
<var class="var">suffix</var>) are prepended (appended) before further transformations
can happen with a special transformation script <var class="var">pattern</var>.
</p>
<p>As currently implemented, this option only takes effect for native
builds; cross compiler binaries&rsquo; names are not transformed even when a
transformation is explicitly asked for by one of these options.
</p>
<p>For native builds, some of the installed programs are also installed
with the target alias in front of their name, as in
&lsquo;<samp class="samp">i686-pc-linux-gnu-gcc</samp>&rsquo;.  All of the above transformations happen
before the target alias is prepended to the name&mdash;so, specifying
<samp class="option">--program-prefix=foo-</samp> and <samp class="option">program-suffix=-3.1</samp>, the
resulting binary would be installed as
<samp class="file">/usr/local/bin/i686-pc-linux-gnu-foo-gcc-3.1</samp>.
</p>
<p>As a last shortcoming, none of the installed Ada programs are
transformed yet, which will be fixed in some time.
</p>
</dd>
<dt><code class="code">--with-local-prefix=<var class="var">dirname</var></code></dt>
<dd><p>Specify the
installation directory for local include files.  The default is
<samp class="file">/usr/local</samp>.  Specify this option if you want the compiler to
search directory <samp class="file"><var class="var">dirname</var>/include</samp> for locally installed
header files <em class="emph">instead</em> of <samp class="file">/usr/local/include</samp>.
</p>
<p>You should specify <samp class="option">--with-local-prefix</samp> <strong class="strong">only</strong> if your
site has a different convention (not <samp class="file">/usr/local</samp>) for where to put
site-specific files.
</p>
<p>The default value for <samp class="option">--with-local-prefix</samp> is <samp class="file">/usr/local</samp>
regardless of the value of <samp class="option">--prefix</samp>.  Specifying
<samp class="option">--prefix</samp> has no effect on which directory GCC searches for
local header files.  This may seem counterintuitive, but actually it is
logical.
</p>
<p>The purpose of <samp class="option">--prefix</samp> is to specify where to <em class="emph">install
GCC</em>.  The local header files in <samp class="file">/usr/local/include</samp>&mdash;if you put
any in that directory&mdash;are not part of GCC.  They are part of other
programs&mdash;perhaps many others.  (GCC installs its own header files in
another directory which is based on the <samp class="option">--prefix</samp> value.)
</p>
<p>Both the local-prefix include directory and the GCC-prefix include
directory are part of GCC&rsquo;s &ldquo;system include&rdquo; directories.  Although these
two directories are not fixed, they need to be searched in the proper
order for the correct processing of the include_next directive.  The
local-prefix include directory is searched before the GCC-prefix
include directory.  Another characteristic of system include directories
is that pedantic warnings are turned off for headers in these directories.
</p>
<p>Some autoconf macros add <samp class="option">-I <var class="var">directory</var></samp> options to the
compiler command line, to ensure that directories containing installed
packages&rsquo; headers are searched.  When <var class="var">directory</var> is one of GCC&rsquo;s
system include directories, GCC will ignore the option so that system
directories continue to be processed in the correct order.  This
may result in a search order different from what was specified but the
directory will still be searched.
</p>
<p>GCC automatically searches for ordinary libraries using
<code class="env">GCC_EXEC_PREFIX</code>.  Thus, when the same installation prefix is
used for both GCC and packages, GCC will automatically search for
both headers and libraries.  This provides a configuration that is
easy to use.  GCC behaves in a manner similar to that when it is
installed as a system compiler in <samp class="file">/usr</samp>.
</p>
<p>Sites that need to install multiple versions of GCC may not want to
use the above simple configuration.  It is possible to use the
<samp class="option">--program-prefix</samp>, <samp class="option">--program-suffix</samp> and
<samp class="option">--program-transform-name</samp> options to install multiple versions
into a single directory, but it may be simpler to use different prefixes
and the <samp class="option">--with-local-prefix</samp> option to specify the location of the
site-specific files for each version.  It will then be necessary for
users to specify explicitly the location of local site libraries
(e.g., with <code class="env">LIBRARY_PATH</code>).
</p>
<p>The same value can be used for both <samp class="option">--with-local-prefix</samp> and
<samp class="option">--prefix</samp> provided it is not <samp class="file">/usr</samp>.  This can be used
to avoid the default search of <samp class="file">/usr/local/include</samp>.
</p>
<p><strong class="strong">Do not</strong> specify <samp class="file">/usr</samp> as the <samp class="option">--with-local-prefix</samp>!
The directory you use for <samp class="option">--with-local-prefix</samp> <strong class="strong">must not</strong>
contain any of the system&rsquo;s standard header files.  If it did contain
them, certain programs would be miscompiled (including GNU Emacs, on
certain targets), because this would override and nullify the header
file corrections made by the <code class="command">fixincludes</code> script.
</p>
<p>Indications are that people who use this option use it based on mistaken
ideas of what it is for.  People use it as if it specified where to
install part of GCC.  Perhaps they make this assumption because
installing GCC creates the directory.
</p>
</dd>
<dt><code class="code">--with-gcc-major-version-only</code></dt>
<dd><p>Specifies that GCC should use only the major number rather than
<var class="var">major</var>.<var class="var">minor</var>.<var class="var">patchlevel</var> in filesystem paths.
</p>
</dd>
<dt><code class="code">--with-native-system-header-dir=<var class="var">dirname</var></code></dt>
<dd><p>Specifies that <var class="var">dirname</var> is the directory that contains native system
header files, rather than <samp class="file">/usr/include</samp>.  This option is most useful
if you are creating a compiler that should be isolated from the system
as much as possible.  It is most commonly used with the
<samp class="option">--with-sysroot</samp> option and will cause GCC to search
<var class="var">dirname</var> inside the system root specified by that option.
</p>
</dd>
<dt><code class="code">--enable-shared[=<var class="var">package</var>[,&hellip;]]</code></dt>
<dd><p>Build shared versions of libraries, if shared libraries are supported on
the target platform.  Unlike GCC 2.95.x and earlier, shared libraries
are enabled by default on all platforms that support shared libraries.
</p>
<p>If a list of packages is given as an argument, build shared libraries
only for the listed packages.  For other packages, only static libraries
will be built.  Package names currently recognized in the GCC tree are
&lsquo;<samp class="samp">libgcc</samp>&rsquo; (also known as &lsquo;<samp class="samp">gcc</samp>&rsquo;), &lsquo;<samp class="samp">libstdc++</samp>&rsquo; (not
&lsquo;<samp class="samp">libstdc++-v3</samp>&rsquo;), &lsquo;<samp class="samp">libffi</samp>&rsquo;, &lsquo;<samp class="samp">zlib</samp>&rsquo;, &lsquo;<samp class="samp">boehm-gc</samp>&rsquo;,
&lsquo;<samp class="samp">ada</samp>&rsquo;, &lsquo;<samp class="samp">libada</samp>&rsquo;, &lsquo;<samp class="samp">libgo</samp>&rsquo;, &lsquo;<samp class="samp">libobjc</samp>&rsquo;, and &lsquo;<samp class="samp">libphobos</samp>&rsquo;.
Note &lsquo;<samp class="samp">libiberty</samp>&rsquo; does not support shared libraries at all.
</p>
<p>Use <samp class="option">--disable-shared</samp> to build only static libraries.  Note that
<samp class="option">--disable-shared</samp> does not accept a list of package names as
argument, only <samp class="option">--enable-shared</samp> does.
</p>
<p>Contrast with <samp class="option">--enable-host-shared</samp>, which affects <em class="emph">host</em>
code.
</p>
</dd>
<dt><code class="code">--enable-host-shared</code></dt>
<dd><p>Specify that the <em class="emph">host</em> code should be built into position-independent
machine code (with -fPIC), allowing it to be used within shared libraries,
but yielding a slightly slower compiler.
</p>
<p>This option is required when building the libgccjit.so library.
</p>
<p>Contrast with <samp class="option">--enable-shared</samp>, which affects <em class="emph">target</em>
libraries.
</p>
</dd>
<dt><code class="code"><a class="anchor" id="with-gnu-as"></a>--with-gnu-as</code></dt>
<dd><p>Specify that the compiler should assume that the
assembler it finds is the GNU assembler.  However, this does not modify
the rules to find an assembler and will result in confusion if the
assembler found is not actually the GNU assembler.  (Confusion may also
result if the compiler finds the GNU assembler but has not been
configured with <samp class="option">--with-gnu-as</samp>.)  If you have more than one
assembler installed on your system, you may want to use this option in
connection with <samp class="option">--with-as=<var class="var">pathname</var></samp> or
<samp class="option">--with-build-time-tools=<var class="var">pathname</var></samp>.
</p>
<p>The following systems are the only ones where it makes a difference
whether you use the GNU assembler.  On any other system,
<samp class="option">--with-gnu-as</samp> has no effect.
</p>
<ul class="itemize mark-bullet">
<li>&lsquo;<samp class="samp">hppa1.0-<var class="var">any</var>-<var class="var">any</var></samp>&rsquo;
</li><li>&lsquo;<samp class="samp">hppa1.1-<var class="var">any</var>-<var class="var">any</var></samp>&rsquo;
</li><li>&lsquo;<samp class="samp">*-*-solaris2.11</samp>&rsquo;
</li></ul>

</dd>
<dt><code class="code"><a class="anchor" id="with-as"></a>--with-as=<var class="var">pathname</var></code></dt>
<dd><p>Specify that the compiler should use the assembler pointed to by
<var class="var">pathname</var>, rather than the one found by the standard rules to find
an assembler, which are:
</p><ul class="itemize mark-bullet">
<li>Unless GCC is being built with a cross compiler, check the
<samp class="file"><var class="var">libexec</var>/gcc/<var class="var">target</var>/<var class="var">version</var></samp> directory.
<var class="var">libexec</var> defaults to <samp class="file"><var class="var">exec-prefix</var>/libexec</samp>;
<var class="var">exec-prefix</var> defaults to <var class="var">prefix</var>, which
defaults to <samp class="file">/usr/local</samp> unless overridden by the
<samp class="option">--prefix=<var class="var">pathname</var></samp> switch described above.  <var class="var">target</var>
is the target system triple, such as &lsquo;<samp class="samp">sparc-sun-solaris2.11</samp>&rsquo;, and
<var class="var">version</var> denotes the GCC version, such as 3.0.

</li><li>If the target system is the same that you are building on, check
operating system specific directories.

</li><li>Check in the <code class="env">PATH</code> for a tool whose name is prefixed by the
target system triple.

</li><li>Check in the <code class="env">PATH</code> for a tool whose name is not prefixed by the
target system triple, if the host and target system triple are
the same (in other words, we use a host tool if it can be used for
the target as well).
</li></ul>

<p>You may want to use <samp class="option">--with-as</samp> if no assembler
is installed in the directories listed above, or if you have multiple
assemblers installed and want to choose one that is not found by the
above rules.
</p>
</dd>
<dt><code class="code"><a class="anchor" id="with-gnu-ld"></a>--with-gnu-ld</code></dt>
<dd><p>Same as <a class="uref" href="#with-gnu-as"><samp class="option">--with-gnu-as</samp></a>
but for the linker.
</p>
</dd>
<dt><code class="code">--with-ld=<var class="var">pathname</var></code></dt>
<dd><p>Same as <a class="uref" href="#with-as"><samp class="option">--with-as</samp></a>
but for the linker.
</p>
</dd>
<dt><code class="code">--with-dsymutil=<var class="var">pathname</var></code></dt>
<dd><p>Same as <a class="uref" href="#with-as"><samp class="option">--with-as</samp></a>
but for the debug linker (only used on Darwin platforms so far).
</p>
</dd>
<dt><code class="code">--with-tls=<var class="var">dialect</var></code></dt>
<dd><p>Specify the default TLS dialect, for systems were there is a choice.
For ARM targets, possible values for <var class="var">dialect</var> are <code class="code">gnu</code> or
<code class="code">gnu2</code>, which select between the original GNU dialect and the GNU TLS
descriptor-based dialect.
</p>
</dd>
<dt><code class="code">--enable-multiarch</code></dt>
<dd><p>Specify whether to enable or disable multiarch support.  The default is
to check for glibc start files in a multiarch location, and enable it
if the files are found.  The auto detection is enabled for native builds,
and for cross builds configured with <samp class="option">--with-sysroot</samp>, and without
<samp class="option">--with-native-system-header-dir</samp>.
More documentation about multiarch can be found at
<a class="uref" href="https://wiki.debian.org/Multiarch">https://wiki.debian.org/Multiarch</a>.
</p>
</dd>
<dt><code class="code">--enable-sjlj-exceptions</code></dt>
<dd><p>Force use of the <code class="code">setjmp</code>/<code class="code">longjmp</code>-based scheme for exceptions.
&lsquo;<samp class="samp">configure</samp>&rsquo; ordinarily picks the correct value based on the platform.
Only use this option if you are sure you need a different setting.
</p>
</dd>
<dt><code class="code">--enable-vtable-verify</code></dt>
<dd><p>Specify whether to enable or disable the vtable verification feature.
Enabling this feature causes libstdc++ to be built with its virtual calls
in verifiable mode.  This means that, when linked with libvtv, every
virtual call in libstdc++ will verify the vtable pointer through which the
call will be made before actually making the call.  If not linked with libvtv,
the verifier will call stub functions (in libstdc++ itself) and do nothing.
If vtable verification is disabled, then libstdc++ is not built with its
virtual calls in verifiable mode at all.  However the libvtv library will
still be built (see <samp class="option">--disable-libvtv</samp> to turn off building libvtv).
<samp class="option">--disable-vtable-verify</samp> is the default.
</p>
</dd>
<dt><code class="code">--disable-gcov</code></dt>
<dd><p>Specify that the run-time library used for coverage analysis
and associated host tools should not be built.
</p>
</dd>
<dt><code class="code">--disable-multilib</code></dt>
<dd><p>Specify that multiple target
libraries to support different target variants, calling
conventions, etc. should not be built.  The default is to build a
predefined set of them.
</p>
<p>Some targets provide finer-grained control over which multilibs are built
(e.g., <samp class="option">--disable-softfloat</samp>):
</p><dl class="table">
<dt><code class="code">arm-*-*</code></dt>
<dd><p>fpu, 26bit, underscore, interwork, biendian, nofmult.
</p>
</dd>
<dt><code class="code">m68*-*-*</code></dt>
<dd><p>softfloat, m68881, m68000, m68020.
</p>
</dd>
<dt><code class="code">mips*-*-*</code></dt>
<dd><p>single-float, biendian, softfloat.
</p>
</dd>
<dt><code class="code">msp430-*-*</code></dt>
<dd><p>no-exceptions
</p>
</dd>
<dt><code class="code">powerpc*-*-*, rs6000*-*-*</code></dt>
<dd><p>aix64, pthread, softfloat, powercpu, powerpccpu, powerpcos, biendian,
sysv, aix.
</p>
</dd>
</dl>

</dd>
<dt><code class="code">--with-multilib-list=<var class="var">list</var></code></dt>
<dt><code class="code">--without-multilib-list</code></dt>
<dd><p>Specify what multilibs to build.  <var class="var">list</var> is a comma separated list of
values, possibly consisting of a single value.  Currently only implemented
for aarch64*-*-*, arm*-*-*, loongarch64-*-*, riscv*-*-*, sh*-*-* and
x86-64-*-linux*.  The accepted values and meaning for each target is given
below.
</p>
<dl class="table">
<dt><code class="code">aarch64*-*-*</code></dt>
<dd><p><var class="var">list</var> is a comma separated list of <code class="code">ilp32</code>, and <code class="code">lp64</code>
to enable ILP32 and LP64 run-time libraries, respectively.  If
<var class="var">list</var> is empty, then there will be no multilibs and only the
default run-time library will be built.  If <var class="var">list</var> is
<code class="code">default</code> or &ndash;with-multilib-list= is not specified, then the
default set of libraries is selected based on the value of
<samp class="option">--target</samp>.
</p>
</dd>
<dt><code class="code">arm*-*-*</code></dt>
<dd><p><var class="var">list</var> is a comma separated list of <code class="code">aprofile</code> and
<code class="code">rmprofile</code> to build multilibs for A or R and M architecture
profiles respectively.  Note that, due to some limitation of the current
multilib framework, using the combined <code class="code">aprofile,rmprofile</code>
multilibs selects in some cases a less optimal multilib than when using
the multilib profile for the architecture targetted.  The special value
<code class="code">default</code> is also accepted and is equivalent to omitting the
option, i.e., only the default run-time library will be enabled.
</p>
<p><var class="var">list</var> may instead contain <code class="code">@name</code>, to use the multilib
configuration Makefile fragment <samp class="file">name</samp> in <samp class="file">gcc/config/arm</samp> in
the source tree (it is part of the corresponding sources, after all).
It is recommended, but not required, that files used for this purpose to
be named starting with <samp class="file">t-ml-</samp>, to make their intended purpose
self-evident, in line with GCC conventions.  Such files enable custom,
user-chosen multilib lists to be configured.  Whether multiple such
files can be used together depends on the contents of the supplied
files.  See <samp class="file">gcc/config/arm/t-multilib</samp> and its supplementary
<samp class="file">gcc/config/arm/t-*profile</samp> files for an example of what such
Makefile fragments might look like for this version of GCC.  The macros
expected to be defined in these fragments are not stable across GCC
releases, so make sure they define the <code class="code">MULTILIB</code>-related macros
expected by the version of GCC you are building.
See &ldquo;Target Makefile Fragments&rdquo; in the internals manual.
</p>
<p>The table below gives the combination of ISAs, architectures, FPUs and
floating-point ABIs for which multilibs are built for each predefined
profile.  The union of these options is considered when specifying both
<code class="code">aprofile</code> and <code class="code">rmprofile</code>.
</p>
<table class="multitable">
<tbody><tr><td width="15%">Option</td><td width="28%">aprofile</td><td width="30%">rmprofile</td></tr>
<tr><td width="15%">ISAs</td><td width="28%"><code class="code">-marm</code> and <code class="code">-mthumb</code></td><td width="30%"><code class="code">-mthumb</code></td></tr>
<tr><td width="15%">Architectures<br><br><br><br><br><br></td><td width="28%">default architecture<br>
<code class="code">-march=armv7-a</code><br>
<code class="code">-march=armv7ve</code><br>
<code class="code">-march=armv8-a</code><br><br><br></td><td width="30%">default architecture<br>
<code class="code">-march=armv6s-m</code><br>
<code class="code">-march=armv7-m</code><br>
<code class="code">-march=armv7e-m</code><br>
<code class="code">-march=armv8-m.base</code><br>
<code class="code">-march=armv8-m.main</code><br>
<code class="code">-march=armv7</code></td></tr>
<tr><td width="15%">FPUs<br><br><br><br><br></td><td width="28%">none<br>
<code class="code">-mfpu=vfpv3-d16</code><br>
<code class="code">-mfpu=neon</code><br>
<code class="code">-mfpu=vfpv4-d16</code><br>
<code class="code">-mfpu=neon-vfpv4</code><br>
<code class="code">-mfpu=neon-fp-armv8</code></td><td width="30%">none<br>
<code class="code">-mfpu=vfpv3-d16</code><br>
<code class="code">-mfpu=fpv4-sp-d16</code><br>
<code class="code">-mfpu=fpv5-sp-d16</code><br>
<code class="code">-mfpu=fpv5-d16</code><br></td></tr>
<tr><td width="15%">floating-point ABIs<br><br></td><td width="28%"><code class="code">-mfloat-abi=soft</code><br>
<code class="code">-mfloat-abi=softfp</code><br>
<code class="code">-mfloat-abi=hard</code></td><td width="30%"><code class="code">-mfloat-abi=soft</code><br>
<code class="code">-mfloat-abi=softfp</code><br>
<code class="code">-mfloat-abi=hard</code></td></tr>
</tbody>
</table>

</dd>
<dt><code class="code">loongarch*-*-*</code></dt>
<dd><p><var class="var">list</var> is a comma-separated list of the following ABI identifiers:
<code class="code">lp64d[/base]</code> <code class="code">lp64f[/base]</code> <code class="code">lp64d[/base]</code>, where the
<code class="code">/base</code> suffix may be omitted, to enable their respective run-time
libraries.  If <var class="var">list</var> is empty or <code class="code">default</code>,
or if <samp class="option">--with-multilib-list</samp> is not specified, then the default ABI
as specified by <samp class="option">--with-abi</samp> or implied by <samp class="option">--target</samp> is selected.
</p>
</dd>
<dt><code class="code">riscv*-*-*</code></dt>
<dd><p><var class="var">list</var> is a single ABI name.  The target architecture must be either
<code class="code">rv32gc</code> or <code class="code">rv64gc</code>.  This will build a single multilib for the
specified architecture and ABI pair.  If <code class="code">--with-multilib-list</code> is not
given, then a default set of multilibs is selected based on the value of
<samp class="option">--target</samp>.  This is usually a large set of multilibs.
</p>
</dd>
<dt><code class="code">sh*-*-*</code></dt>
<dd><p><var class="var">list</var> is a comma separated list of CPU names.  These must be of the
form <code class="code">sh*</code> or <code class="code">m*</code> (in which case they match the compiler option
for that processor).  The list should not contain any endian options -
these are handled by <samp class="option">--with-endian</samp>.
</p>
<p>If <var class="var">list</var> is empty, then there will be no multilibs for extra
processors.  The multilib for the secondary endian remains enabled.
</p>
<p>As a special case, if an entry in the list starts with a <code class="code">!</code>
(exclamation point), then it is added to the list of excluded multilibs.
Entries of this sort should be compatible with &lsquo;<samp class="samp">MULTILIB_EXCLUDES</samp>&rsquo;
(once the leading <code class="code">!</code> has been stripped).
</p>
<p>If <samp class="option">--with-multilib-list</samp> is not given, then a default set of
multilibs is selected based on the value of <samp class="option">--target</samp>.  This is
usually the complete set of libraries, but some targets imply a more
specialized subset.
</p>
<p>Example 1: to configure a compiler for SH4A only, but supporting both
endians, with little endian being the default:
</p><div class="example smallexample">
<pre class="example-preformatted">--with-cpu=sh4a --with-endian=little,big --with-multilib-list=
</pre></div>

<p>Example 2: to configure a compiler for both SH4A and SH4AL-DSP, but with
only little endian SH4AL:
</p><div class="example smallexample">
<pre class="example-preformatted">--with-cpu=sh4a --with-endian=little,big \
--with-multilib-list=sh4al,!mb/m4al
</pre></div>

</dd>
<dt><code class="code">x86-64-*-linux*</code></dt>
<dd><p><var class="var">list</var> is a comma separated list of <code class="code">m32</code>, <code class="code">m64</code> and
<code class="code">mx32</code> to enable 32-bit, 64-bit and x32 run-time libraries,
respectively.  If <var class="var">list</var> is empty, then there will be no multilibs
and only the default run-time library will be enabled.
</p>
<p>If <samp class="option">--with-multilib-list</samp> is not given, then only 32-bit and
64-bit run-time libraries will be enabled.
</p></dd>
</dl>

</dd>
<dt><code class="code">--with-multilib-generator=<var class="var">config</var></code></dt>
<dd><p>Specify what multilibs to build.  <var class="var">config</var> is a semicolon separated list of
values, possibly consisting of a single value.  Currently only implemented
for riscv*-*-elf*.  The accepted values and meanings are given below.
</p>

<p>Every config is constructed with four components: architecture string, ABI,
reuse rule with architecture string and reuse rule with sub-extension.
</p>
<p>Example 1: Add multi-lib suppport for rv32i with ilp32.
</p><div class="example smallexample">
<pre class="example-preformatted">rv32i-ilp32--
</pre></div>

<p>Example 2: Add multi-lib suppport for rv32i with ilp32 and rv32imafd with ilp32.
</p><div class="example smallexample">
<pre class="example-preformatted">rv32i-ilp32--;rv32imafd-ilp32--
</pre></div>

<p>Example 3: Add multi-lib suppport for rv32i with ilp32; rv32im with ilp32 and
rv32ic with ilp32 will reuse this multi-lib set.
</p><div class="example smallexample">
<pre class="example-preformatted">rv32i-ilp32-rv32im-c
</pre></div>

<p>Example 4: Add multi-lib suppport for rv64ima with lp64; rv64imaf with lp64,
rv64imac with lp64 and rv64imafc with lp64 will reuse this multi-lib set.
</p><div class="example smallexample">
<pre class="example-preformatted">rv64ima-lp64--f,c,fc
</pre></div>

<p><samp class="option">--with-multilib-generator</samp> have an optional configuration argument
<samp class="option">--cmodel=val</samp> for code model, this option will expand with other
config options, <var class="var">val</var> is a comma separated list of possible code model,
currently we support medlow and medany.
</p>
<p>Example 5: Add multi-lib suppport for rv64ima with lp64; rv64ima with lp64 and
medlow code model
</p><div class="example smallexample">
<pre class="example-preformatted">rv64ima-lp64--;--cmodel=medlow
</pre></div>

<p>Example 6: Add multi-lib suppport for rv64ima with lp64; rv64ima with lp64 and
medlow code model; rv64ima with lp64 and medany code model
</p><div class="example smallexample">
<pre class="example-preformatted">rv64ima-lp64--;--cmodel=medlow,medany
</pre></div>

</dd>
<dt><code class="code">--with-endian=<var class="var">endians</var></code></dt>
<dd><p>Specify what endians to use.
Currently only implemented for sh*-*-*.
</p>
<p><var class="var">endians</var> may be one of the following:
</p><dl class="table">
<dt><code class="code">big</code></dt>
<dd><p>Use big endian exclusively.
</p></dd>
<dt><code class="code">little</code></dt>
<dd><p>Use little endian exclusively.
</p></dd>
<dt><code class="code">big,little</code></dt>
<dd><p>Use big endian by default.  Provide a multilib for little endian.
</p></dd>
<dt><code class="code">little,big</code></dt>
<dd><p>Use little endian by default.  Provide a multilib for big endian.
</p></dd>
</dl>

</dd>
<dt><code class="code">--enable-threads</code></dt>
<dd><p>Specify that the target
supports threads.  This affects the Objective-C compiler and runtime
library, and exception handling for other languages like C++.
On some systems, this is the default.
</p>
<p>In general, the best (and, in many cases, the only known) threading
model available will be configured for use.  Beware that on some
systems, GCC has not been taught what threading models are generally
available for the system.  In this case, <samp class="option">--enable-threads</samp> is an
alias for <samp class="option">--enable-threads=single</samp>.
</p>
</dd>
<dt><code class="code">--disable-threads</code></dt>
<dd><p>Specify that threading support should be disabled for the system.
This is an alias for <samp class="option">--enable-threads=single</samp>.
</p>
</dd>
<dt><code class="code">--enable-threads=<var class="var">lib</var></code></dt>
<dd><p>Specify that
<var class="var">lib</var> is the thread support library.  This affects the Objective-C
compiler and runtime library, and exception handling for other languages
like C++.  The possibilities for <var class="var">lib</var> are:
</p>
<dl class="table">
<dt><code class="code">aix</code></dt>
<dd><p>AIX thread support.
</p></dd>
<dt><code class="code">dce</code></dt>
<dd><p>DCE thread support.
</p></dd>
<dt><code class="code">lynx</code></dt>
<dd><p>LynxOS thread support.
</p></dd>
<dt><code class="code">mipssde</code></dt>
<dd><p>MIPS SDE thread support.
</p></dd>
<dt><code class="code">no</code></dt>
<dd><p>This is an alias for &lsquo;<samp class="samp">single</samp>&rsquo;.
</p></dd>
<dt><code class="code">posix</code></dt>
<dd><p>Generic POSIX/Unix98 thread support.
</p></dd>
<dt><code class="code">rtems</code></dt>
<dd><p>RTEMS thread support.
</p></dd>
<dt><code class="code">single</code></dt>
<dd><p>Disable thread support, should work for all platforms.
</p></dd>
<dt><code class="code">tpf</code></dt>
<dd><p>TPF thread support.
</p></dd>
<dt><code class="code">vxworks</code></dt>
<dd><p>VxWorks thread support.
</p></dd>
<dt><code class="code">win32</code></dt>
<dd><p>Microsoft Win32 API thread support.
</p></dd>
</dl>

</dd>
<dt><code class="code">--enable-tls</code></dt>
<dd><p>Specify that the target supports TLS (Thread Local Storage).  Usually
configure can correctly determine if TLS is supported.  In cases where
it guesses incorrectly, TLS can be explicitly enabled or disabled with
<samp class="option">--enable-tls</samp> or <samp class="option">--disable-tls</samp>.  This can happen if
the assembler supports TLS but the C library does not, or if the
assumptions made by the configure test are incorrect.
</p>
</dd>
<dt><code class="code">--disable-tls</code></dt>
<dd><p>Specify that the target does not support TLS.
This is an alias for <samp class="option">--enable-tls=no</samp>.
</p>
</dd>
<dt><code class="code">--disable-tm-clone-registry</code></dt>
<dd><p>Disable TM clone registry in libgcc. It is enabled in libgcc by default.
This option helps to reduce code size for embedded targets which do
not use transactional memory.
</p>
</dd>
<dt><code class="code">--with-cpu=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-cpu-32=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-cpu-64=<var class="var">cpu</var></code></dt>
<dd><p>Specify which cpu variant the compiler should generate code for by default.
<var class="var">cpu</var> will be used as the default value of the <samp class="option">-mcpu=</samp> switch.
This option is only supported on some targets, including ARC, ARM, i386, M68k,
PowerPC, and SPARC.  It is mandatory for ARC.  The <samp class="option">--with-cpu-32</samp> and
<samp class="option">--with-cpu-64</samp> options specify separate default CPUs for
32-bit and 64-bit modes; these options are only supported for aarch64, i386,
x86-64, PowerPC, and SPARC.
</p>
</dd>
<dt><code class="code">--with-schedule=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-arch=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-arch-32=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-arch-64=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-tune=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-tune-32=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-tune-64=<var class="var">cpu</var></code></dt>
<dt><code class="code">--with-abi=<var class="var">abi</var></code></dt>
<dt><code class="code">--with-fpu=<var class="var">type</var></code></dt>
<dt><code class="code">--with-float=<var class="var">type</var></code></dt>
<dd><p>These configure options provide default values for the <samp class="option">-mschedule=</samp>,
<samp class="option">-march=</samp>, <samp class="option">-mtune=</samp>, <samp class="option">-mabi=</samp>, and <samp class="option">-mfpu=</samp>
options and for <samp class="option">-mhard-float</samp> or <samp class="option">-msoft-float</samp>.  As with
<samp class="option">--with-cpu</samp>, which switches will be accepted and acceptable values
of the arguments depend on the target.
</p>
</dd>
<dt><code class="code">--with-mode=<var class="var">mode</var></code></dt>
<dd><p>Specify if the compiler should default to <samp class="option">-marm</samp> or <samp class="option">-mthumb</samp>.
This option is only supported on ARM targets.
</p>
</dd>
<dt><code class="code">--with-stack-offset=<var class="var">num</var></code></dt>
<dd><p>This option sets the default for the -mstack-offset=<var class="var">num</var> option,
and will thus generally also control the setting of this option for
libraries.  This option is only supported on Epiphany targets.
</p>
</dd>
<dt><code class="code">--with-fpmath=<var class="var">isa</var></code></dt>
<dd><p>This options sets <samp class="option">-mfpmath=sse</samp> by default and specifies the default
ISA for floating-point arithmetics.  You can select either &lsquo;<samp class="samp">sse</samp>&rsquo; which
enables <samp class="option">-msse2</samp> or &lsquo;<samp class="samp">avx</samp>&rsquo; which enables <samp class="option">-mavx</samp> by default.
This option is only supported on i386 and x86-64 targets.
</p>
</dd>
<dt><code class="code">--with-fp-32=<var class="var">mode</var></code></dt>
<dd><p>On MIPS targets, set the default value for the <samp class="option">-mfp</samp> option when using
the o32 ABI.  The possibilities for <var class="var">mode</var> are:
</p><dl class="table">
<dt><code class="code">32</code></dt>
<dd><p>Use the o32 FP32 ABI extension, as with the <samp class="option">-mfp32</samp> command-line
option.
</p></dd>
<dt><code class="code">xx</code></dt>
<dd><p>Use the o32 FPXX ABI extension, as with the <samp class="option">-mfpxx</samp> command-line
option.
</p></dd>
<dt><code class="code">64</code></dt>
<dd><p>Use the o32 FP64 ABI extension, as with the <samp class="option">-mfp64</samp> command-line
option.
</p></dd>
</dl>
<p>In the absence of this configuration option the default is to use the o32
FP32 ABI extension.
</p>
</dd>
<dt><code class="code">--with-odd-spreg-32</code></dt>
<dd><p>On MIPS targets, set the <samp class="option">-modd-spreg</samp> option by default when using
the o32 ABI.
</p>
</dd>
<dt><code class="code">--without-odd-spreg-32</code></dt>
<dd><p>On MIPS targets, set the <samp class="option">-mno-odd-spreg</samp> option by default when using
the o32 ABI.  This is normally used in conjunction with
<samp class="option">--with-fp-32=64</samp> in order to target the o32 FP64A ABI extension.
</p>
</dd>
<dt><code class="code">--with-nan=<var class="var">encoding</var></code></dt>
<dd><p>On MIPS targets, set the default encoding convention to use for the
special not-a-number (NaN) IEEE 754 floating-point data.  The
possibilities for <var class="var">encoding</var> are:
</p><dl class="table">
<dt><code class="code">legacy</code></dt>
<dd><p>Use the legacy encoding, as with the <samp class="option">-mnan=legacy</samp> command-line
option.
</p></dd>
<dt><code class="code">2008</code></dt>
<dd><p>Use the 754-2008 encoding, as with the <samp class="option">-mnan=2008</samp> command-line
option.
</p></dd>
</dl>
<p>To use this configuration option you must have an assembler version
installed that supports the <samp class="option">-mnan=</samp> command-line option too.
In the absence of this configuration option the default convention is
the legacy encoding, as when neither of the <samp class="option">-mnan=2008</samp> and
<samp class="option">-mnan=legacy</samp> command-line options has been used.
</p>
</dd>
<dt><code class="code">--with-divide=<var class="var">type</var></code></dt>
<dd><p>Specify how the compiler should generate code for checking for
division by zero.  This option is only supported on the MIPS target.
The possibilities for <var class="var">type</var> are:
</p><dl class="table">
<dt><code class="code">traps</code></dt>
<dd><p>Division by zero checks use conditional traps (this is the default on
systems that support conditional traps).
</p></dd>
<dt><code class="code">breaks</code></dt>
<dd><p>Division by zero checks use the break instruction.
</p></dd>
</dl>

</dd>
<dt><code class="code">--with-compact-branches=<var class="var">policy</var></code></dt>
<dd><p>Specify how the compiler should generate branch instructions.
This option is only supported on the MIPS target.
The possibilities for <var class="var">type</var> are:
</p><dl class="table">
<dt><code class="code">optimal</code></dt>
<dd><p>Cause a delay slot branch to be used if one is available in the
current ISA and the delay slot is successfully filled. If the delay slot
is not filled, a compact branch will be chosen if one is available.
</p></dd>
<dt><code class="code">never</code></dt>
<dd><p>Ensures that compact branch instructions will never be generated.
</p></dd>
<dt><code class="code">always</code></dt>
<dd><p>Ensures that a compact branch instruction will be generated if available.
If a compact branch instruction is not available,
a delay slot form of the branch will be used instead.
This option is supported from MIPS Release 6 onwards.
For pre-R6/microMIPS/MIPS16, this option is just same as never/optimal.
</p></dd>
</dl>


</dd>
<dt><code class="code">--with-llsc</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mllsc</samp> the default when no
<samp class="option">-mno-llsc</samp> option is passed.  This is the default for
Linux-based targets, as the kernel will emulate them if the ISA does
not provide them.
</p>
</dd>
<dt><code class="code">--without-llsc</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mno-llsc</samp> the default when no
<samp class="option">-mllsc</samp> option is passed.
</p>
</dd>
<dt><code class="code">--with-synci</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-msynci</samp> the default when no
<samp class="option">-mno-synci</samp> option is passed.
</p>
</dd>
<dt><code class="code">--without-synci</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mno-synci</samp> the default when no
<samp class="option">-msynci</samp> option is passed.  This is the default.
</p>
</dd>
<dt><code class="code">--with-lxc1-sxc1</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mlxc1-sxc1</samp> the default when no
<samp class="option">-mno-lxc1-sxc1</samp> option is passed.  This is the default.
</p>
</dd>
<dt><code class="code">--without-lxc1-sxc1</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mno-lxc1-sxc1</samp> the default when no
<samp class="option">-mlxc1-sxc1</samp> option is passed.  The indexed load/store
instructions are not directly a problem but can lead to unexpected
behaviour when deployed in an application intended for a 32-bit address
space but run on a 64-bit processor.  The issue is seen because all
known MIPS 64-bit Linux kernels execute o32 and n32 applications
with 64-bit addressing enabled which affects the overflow behaviour
of the indexed addressing mode.  GCC will assume that ordinary
32-bit arithmetic overflow behaviour is the same whether performed
as an <code class="code">addu</code> instruction or as part of the address calculation
in <code class="code">lwxc1</code> type instructions.  This assumption holds true in a
pure 32-bit environment and can hold true in a 64-bit environment if
the address space is accurately set to be 32-bit for o32 and n32.
</p>
</dd>
<dt><code class="code">--with-madd4</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mmadd4</samp> the default when no
<samp class="option">-mno-madd4</samp> option is passed.  This is the default.
</p>
</dd>
<dt><code class="code">--without-madd4</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mno-madd4</samp> the default when no
<samp class="option">-mmadd4</samp> option is passed.  The <code class="code">madd4</code> instruction
family can be problematic when targeting a combination of cores that
implement these instructions differently.  There are two known cores
that implement these as fused operations instead of unfused (where
unfused is normally expected).  Disabling these instructions is the
only way to ensure compatible code is generated; this will incur
a performance penalty.
</p>
</dd>
<dt><code class="code">--with-msa</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mmsa</samp> the default when no
<samp class="option">-mno-msa</samp> option is passed.
</p>
</dd>
<dt><code class="code">--without-msa</code></dt>
<dd><p>On MIPS targets, make <samp class="option">-mno-msa</samp> the default when no
<samp class="option">-mmsa</samp> option is passed. This is the default.
</p>
</dd>
<dt><code class="code">--with-mips-plt</code></dt>
<dd><p>On MIPS targets, make use of copy relocations and PLTs.
These features are extensions to the traditional
SVR4-based MIPS ABIs and require support from GNU binutils
and the runtime C library.
</p>
</dd>
<dt><code class="code">--with-stack-clash-protection-guard-size=<var class="var">size</var></code></dt>
<dd><p>On certain targets this option sets the default stack clash protection guard
size as a power of two in bytes.  On AArch64 <var class="var">size</var> is required to be either
12 (4KB) or 16 (64KB).
</p>
</dd>
<dt><code class="code">--with-isa-spec=<var class="var">ISA-spec-string</var></code></dt>
<dd><p>On RISC-V targets specify the default version of the RISC-V Unprivileged
(formerly User-Level) ISA specification to produce code conforming to.
The possibilities for <var class="var">ISA-spec-string</var> are:
</p><dl class="table">
<dt><code class="code">2.2</code></dt>
<dd><p>Produce code conforming to version 2.2.
</p></dd>
<dt><code class="code">20190608</code></dt>
<dd><p>Produce code conforming to version 20190608.
</p></dd>
<dt><code class="code">20191213</code></dt>
<dd><p>Produce code conforming to version 20191213.
</p></dd>
</dl>
<p>In the absence of this configuration option the default version is 20191213.
</p>
</dd>
<dt><code class="code">--enable-__cxa_atexit</code></dt>
<dd><p>Define if you want to use __cxa_atexit, rather than atexit, to
register C++ destructors for local statics and global objects.
This is essential for fully standards-compliant handling of
destructors, but requires __cxa_atexit in libc.  This option is currently
only available on systems with GNU libc.  When enabled, this will cause
<samp class="option">-fuse-cxa-atexit</samp> to be passed by default.
</p>
</dd>
<dt><code class="code">--enable-gnu-indirect-function</code></dt>
<dd><p>Define if you want to enable the <code class="code">ifunc</code> attribute.  This option is
currently only available on systems with GNU libc on certain targets.
</p>
</dd>
<dt><code class="code">--enable-target-optspace</code></dt>
<dd><p>Specify that target
libraries should be optimized for code space instead of code speed.
This is the default for the m32r platform.
</p>
</dd>
<dt><code class="code">--with-cpp-install-dir=<var class="var">dirname</var></code></dt>
<dd><p>Specify that the user visible <code class="command">cpp</code> program should be installed
in <samp class="file"><var class="var">prefix</var>/<var class="var">dirname</var>/cpp</samp>, in addition to <var class="var">bindir</var>.
</p>
</dd>
<dt><code class="code">--enable-comdat</code></dt>
<dd><p>Enable COMDAT group support.  This is primarily used to override the
automatically detected value.
</p>
</dd>
<dt><code class="code">--enable-initfini-array</code></dt>
<dd><p>Force the use of sections <code class="code">.init_array</code> and <code class="code">.fini_array</code>
(instead of <code class="code">.init</code> and <code class="code">.fini</code>) for constructors and
destructors.  Option <samp class="option">--disable-initfini-array</samp> has the
opposite effect.  If neither option is specified, the configure script
will try to guess whether the <code class="code">.init_array</code> and
<code class="code">.fini_array</code> sections are supported and, if they are, use them.
</p>
</dd>
<dt><code class="code">--enable-link-mutex</code></dt>
<dd><p>When building GCC, use a mutex to avoid linking the compilers for
multiple languages at the same time, to avoid thrashing on build
systems with limited free memory.  The default is not to use such a mutex.
</p>
</dd>
<dt><code class="code">--enable-link-serialization</code></dt>
<dd><p>When building GCC, use make dependencies to serialize linking the compilers for
multiple languages, to avoid thrashing on build
systems with limited free memory.  The default is not to add such
dependencies and thus with parallel make potentially link different
compilers concurrently.  If the argument is a positive integer, allow
that number of concurrent link processes for the large binaries.
</p>
</dd>
<dt><code class="code">--enable-maintainer-mode</code></dt>
<dd><p>The build rules that regenerate the Autoconf and Automake output files as
well as the GCC master message catalog <samp class="file">gcc.pot</samp> are normally
disabled.  This is because it can only be rebuilt if the complete source
tree is present.  If you have changed the sources and want to rebuild the
catalog, configuring with <samp class="option">--enable-maintainer-mode</samp> will enable
this.  Note that you need a recent version of the <code class="code">gettext</code> tools
to do so.
</p>
</dd>
<dt><code class="code">--disable-bootstrap</code></dt>
<dd><p>For a native build, the default configuration is to perform
a 3-stage bootstrap of the compiler when &lsquo;<samp class="samp">make</samp>&rsquo; is invoked,
testing that GCC can compile itself correctly.  If you want to disable
this process, you can configure with <samp class="option">--disable-bootstrap</samp>.
</p>
</dd>
<dt><code class="code">--enable-bootstrap</code></dt>
<dd><p>In special cases, you may want to perform a 3-stage build
even if the target and host triplets are different.
This is possible when the host can run code compiled for
the target (e.g. host is i686-linux, target is i486-linux).
Starting from GCC 4.2, to do this you have to configure explicitly
with <samp class="option">--enable-bootstrap</samp>.
</p>
</dd>
<dt><code class="code">--enable-generated-files-in-srcdir</code></dt>
<dd><p>Neither the .c and .h files that are generated from Bison and flex nor the
info manuals and man pages that are built from the .texi files are present
in the repository development tree.  When building GCC from that development tree,
or from one of our snapshots, those generated files are placed in your
build directory, which allows for the source to be in a readonly
directory.
</p>
<p>If you configure with <samp class="option">--enable-generated-files-in-srcdir</samp> then those
generated files will go into the source directory.  This is mainly intended
for generating release or prerelease tarballs of the GCC sources, since it
is not a requirement that the users of source releases to have flex, Bison,
or makeinfo.
</p>
</dd>
<dt><code class="code">--enable-version-specific-runtime-libs</code></dt>
<dd><p>Specify
that runtime libraries should be installed in the compiler specific
subdirectory (<samp class="file"><var class="var">libdir</var>/gcc</samp>) rather than the usual places.  In
addition, &lsquo;<samp class="samp">libstdc++</samp>&rsquo;&rsquo;s include files will be installed into
<samp class="file"><var class="var">libdir</var></samp> unless you overruled it by using
<samp class="option">--with-gxx-include-dir=<var class="var">dirname</var></samp>.  Using this option is
particularly useful if you intend to use several versions of GCC in
parallel.  The default is &lsquo;<samp class="samp">yes</samp>&rsquo; for &lsquo;<samp class="samp">libada</samp>&rsquo;, and &lsquo;<samp class="samp">no</samp>&rsquo; for
the remaining libraries.
</p>
</dd>
<dt><code class="code"><a class="anchor" id="WithAixSoname"></a>--with-aix-soname=&lsquo;<samp class="samp">aix</samp>&rsquo;, &lsquo;<samp class="samp">svr4</samp>&rsquo; or &lsquo;<samp class="samp">both</samp>&rsquo;</code></dt>
<dd><p>Traditional AIX shared library versioning (versioned <code class="code">Shared Object</code>
files as members of unversioned <code class="code">Archive Library</code> files named
&lsquo;<samp class="samp">lib.a</samp>&rsquo;) causes numerous headaches for package managers. However,
<code class="code">Import Files</code> as members of <code class="code">Archive Library</code> files allow for
<strong class="strong">filename-based versioning</strong> of shared libraries as seen on Linux/SVR4,
where this is called the &quot;SONAME&quot;. But as they prevent static linking,
<code class="code">Import Files</code> may be used with <code class="code">Runtime Linking</code> only, where the
linker does search for &lsquo;<samp class="samp">libNAME.so</samp>&rsquo; before &lsquo;<samp class="samp">libNAME.a</samp>&rsquo; library
filenames with the &lsquo;<samp class="samp">-lNAME</samp>&rsquo; linker flag.
</p>
<a class="anchor" id="AixLdCommand"></a><p>For detailed information please refer to the AIX
<a class="uref" href="https://www.ibm.com/support/knowledgecenter/search/%22the%20ld%20command%2C%20also%20called%20the%20linkage%20editor%20or%20binder%22">ld
Command</a> reference.
</p>
<p>As long as shared library creation is enabled, upon:
</p><dl class="table">
<dt><code class="code">--with-aix-soname=aix</code></dt>
<dt><code class="code">--with-aix-soname=both</code></dt>
<dd><p>A (traditional AIX) <code class="code">Shared Archive Library</code> file is created:
 </p><ul class="itemize mark-bullet">
<li>using the &lsquo;<samp class="samp">libNAME.a</samp>&rsquo; filename scheme
  </li><li>with the <code class="code">Shared Object</code> file as archive member named
  &lsquo;<samp class="samp">libNAME.so.V</samp>&rsquo; (except for &lsquo;<samp class="samp">libgcc_s</samp>&rsquo;, where the <code class="code">Shared
  Object</code> file is named &lsquo;<samp class="samp">shr.o</samp>&rsquo; for backwards compatibility), which
  <ul class="itemize mark-minus">
<li>is used for runtime loading from inside the &lsquo;<samp class="samp">libNAME.a</samp>&rsquo; file
   </li><li>is used for dynamic loading via
   <code class="code">dlopen(&quot;libNAME.a(libNAME.so.V)&quot;, RTLD_MEMBER)</code>
   </li><li>is used for shared linking
   </li><li>is used for static linking, so no separate <code class="code">Static Archive
   Library</code> file is needed
  </li></ul>
</li></ul>
</dd>
<dt><code class="code">--with-aix-soname=both</code></dt>
<dt><code class="code">--with-aix-soname=svr4</code></dt>
<dd><p>A (second) <code class="code">Shared Archive Library</code> file is created:
 </p><ul class="itemize mark-bullet">
<li>using the &lsquo;<samp class="samp">libNAME.so.V</samp>&rsquo; filename scheme
 </li><li>with the <code class="code">Shared Object</code> file as archive member named
 &lsquo;<samp class="samp">shr.o</samp>&rsquo;, which
  <ul class="itemize mark-minus">
<li>is created with the <code class="code">-G linker flag</code>
   </li><li>has the <code class="code">F_LOADONLY</code> flag set
   </li><li>is used for runtime loading from inside the &lsquo;<samp class="samp">libNAME.so.V</samp>&rsquo; file
   </li><li>is used for dynamic loading via <code class="code">dlopen(&quot;libNAME.so.V(shr.o)&quot;,
   RTLD_MEMBER)</code>
  </li></ul>
</li><li>with the <code class="code">Import File</code> as archive member named &lsquo;<samp class="samp">shr.imp</samp>&rsquo;,
 which
  <ul class="itemize mark-minus">
<li>refers to &lsquo;<samp class="samp">libNAME.so.V(shr.o)</samp>&rsquo; as the &quot;SONAME&quot;, to be recorded
   in the <code class="code">Loader Section</code> of subsequent binaries
   </li><li>indicates whether &lsquo;<samp class="samp">libNAME.so.V(shr.o)</samp>&rsquo; is 32 or 64 bit
   </li><li>lists all the public symbols exported by &lsquo;<samp class="samp">lib.so.V(shr.o)</samp>&rsquo;,
   eventually decorated with the <code class="code">&lsquo;<samp class="samp">weak</samp>&rsquo; Keyword</code>
   </li><li>is necessary for shared linking against &lsquo;<samp class="samp">lib.so.V(shr.o)</samp>&rsquo;
   </li></ul>
</li></ul>
<p>A symbolic link using the &lsquo;<samp class="samp">libNAME.so</samp>&rsquo; filename scheme is created:
  </p><ul class="itemize mark-bullet">
<li>pointing to the &lsquo;<samp class="samp">libNAME.so.V</samp>&rsquo; <code class="code">Shared Archive Library</code> file
  </li><li>to permit the <code class="code">ld Command</code> to find &lsquo;<samp class="samp">lib.so.V(shr.imp)</samp>&rsquo; via
  the &lsquo;<samp class="samp">-lNAME</samp>&rsquo; argument (requires <code class="code">Runtime Linking</code> to be enabled)
  </li><li>to permit dynamic loading of &lsquo;<samp class="samp">lib.so.V(shr.o)</samp>&rsquo; without the need
  to specify the version number via <code class="code">dlopen(&quot;libNAME.so(shr.o)&quot;,
  RTLD_MEMBER)</code>
  </li></ul>
</dd>
</dl>

<p>As long as static library creation is enabled, upon:
</p><dl class="table">
<dt><code class="code">--with-aix-soname=svr4</code></dt>
<dd><p>A <code class="code">Static Archive Library</code> is created:
 </p><ul class="itemize mark-bullet">
<li>using the &lsquo;<samp class="samp">libNAME.a</samp>&rsquo; filename scheme
 </li><li>with all the <code class="code">Static Object</code> files as archive members, which
  <ul class="itemize mark-minus">
<li>are used for static linking
  </li></ul>
</li></ul>
</dd>
</dl>

<p>While the aix-soname=&lsquo;<samp class="samp">svr4</samp>&rsquo; option does not create <code class="code">Shared Object</code>
files as members of unversioned <code class="code">Archive Library</code> files any more, package
managers still are responsible to
<a class="uref" href="./specific.html#TransferAixShobj">transfer</a> <code class="code">Shared Object</code> files
found as member of a previously installed unversioned <code class="code">Archive Library</code>
file into the newly installed <code class="code">Archive Library</code> file with the same
filename.
</p>
<p><em class="emph">WARNING:</em> Creating <code class="code">Shared Object</code> files with <code class="code">Runtime Linking</code>
enabled may bloat the TOC, eventually leading to <code class="code">TOC overflow</code> errors,
requiring the use of either the <samp class="option">-Wl,-bbigtoc</samp> linker flag (seen to
break with the <code class="code">GDB</code> debugger) or some of the TOC-related compiler flags,
see &ldquo;RS/6000 and PowerPC Options&rdquo; in the main manual.
</p>
<p><samp class="option">--with-aix-soname</samp> is currently supported by &lsquo;<samp class="samp">libgcc_s</samp>&rsquo; only, so
this option is still experimental and not for normal use yet.
</p>
<p>Default is the traditional behavior <samp class="option">--with-aix-soname=&lsquo;<samp class="samp">aix</samp>&rsquo;</samp>.
</p>
</dd>
<dt><code class="code">--enable-languages=<var class="var">lang1</var>,<var class="var">lang2</var>,&hellip;</code></dt>
<dd><p>Specify that only a particular subset of compilers and
their runtime libraries should be built.  For a list of valid values for
<var class="var">langN</var> you can issue the following command in the
<samp class="file">gcc</samp> directory of your GCC source tree:<br>
</p><div class="example smallexample">
<pre class="example-preformatted">grep ^language= */config-lang.in
</pre></div>
<p>Currently, you can use any of the following:
<code class="code">all</code>, <code class="code">default</code>, <code class="code">ada</code>, <code class="code">c</code>, <code class="code">c++</code>, <code class="code">d</code>,
<code class="code">fortran</code>, <code class="code">go</code>, <code class="code">jit</code>, <code class="code">lto</code>, <code class="code">m2</code>,
<code class="code">objc</code>, <code class="code">obj-c++</code>.
Building the Ada compiler has special requirements, see below.
If you do not pass this flag, or specify the option <code class="code">default</code>, then the
default languages available in the <samp class="file">gcc</samp> sub-tree will be configured.
Ada, D, Go, Jit, Objective-C++ and Modula-2 are not default languages.
LTO is not a
default language, but is built by default because <samp class="option">--enable-lto</samp> is
enabled by default.  The other languages are default languages.  If
<code class="code">all</code> is specified, then all available languages are built.  An
exception is <code class="code">jit</code> language, which requires
<samp class="option">--enable-host-shared</samp> to be included with <code class="code">all</code>.
</p>
</dd>
<dt><code class="code">--enable-stage1-languages=<var class="var">lang1</var>,<var class="var">lang2</var>,&hellip;</code></dt>
<dd><p>Specify that a particular subset of compilers and their runtime
libraries should be built with the system C compiler during stage 1 of
the bootstrap process, rather than only in later stages with the
bootstrapped C compiler.  The list of valid values is the same as for
<samp class="option">--enable-languages</samp>, and the option <code class="code">all</code> will select all
of the languages enabled by <samp class="option">--enable-languages</samp>.  This option is
primarily useful for GCC development; for instance, when a development
version of the compiler cannot bootstrap due to compiler bugs, or when
one is debugging front ends other than the C front end.  When this
option is used, one can then build the target libraries for the
specified languages with the stage-1 compiler by using <code class="command">make
stage1-bubble all-target</code>, or run the testsuite on the stage-1 compiler
for the specified languages using <code class="command">make stage1-start check-gcc</code>.
</p>
</dd>
<dt><code class="code">--disable-libada</code></dt>
<dd><p>Specify that the run-time libraries and tools used by GNAT should not
be built.  This can be useful for debugging, or for compatibility with
previous Ada build procedures, when it was required to explicitly
do a &lsquo;<samp class="samp">make -C gcc gnatlib_and_tools</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">--disable-libgm2</code></dt>
<dd><p>Specify that the run-time libraries and tools used by Modula-2 should not
be built.  This can be useful for debugging.
</p>
</dd>
<dt><code class="code">--disable-libsanitizer</code></dt>
<dd><p>Specify that the run-time libraries for the various sanitizers should
not be built.
</p>
</dd>
<dt><code class="code">--disable-libssp</code></dt>
<dd><p>Specify that the run-time libraries for stack smashing protection
should not be built or linked against.  On many targets library support
is provided by the C library instead.
</p>
</dd>
<dt><code class="code">--disable-libquadmath</code></dt>
<dd><p>Specify that the GCC quad-precision math library should not be built.
On some systems, the library is required to be linkable when building
the Fortran front end, unless <samp class="option">--disable-libquadmath-support</samp>
is used.
</p>
</dd>
<dt><code class="code">--disable-libquadmath-support</code></dt>
<dd><p>Specify that the Fortran front end and <code class="code">libgfortran</code> do not add
support for <code class="code">libquadmath</code> on systems supporting it.
</p>
</dd>
<dt><code class="code">--disable-libgomp</code></dt>
<dd><p>Specify that the GNU Offloading and Multi Processing Runtime Library
should not be built.
</p>
</dd>
<dt><code class="code">--disable-libvtv</code></dt>
<dd><p>Specify that the run-time libraries used by vtable verification
should not be built.
</p>
</dd>
<dt><code class="code">--with-dwarf2</code></dt>
<dd><p>Specify that the compiler should
use DWARF debugging information as the default; the exact
DWARF version that is the default is target-specific.
</p>
</dd>
<dt><code class="code">--with-advance-toolchain=<var class="var">at</var></code></dt>
<dd><p>On 64-bit PowerPC Linux systems, configure the compiler to use the
header files, library files, and the dynamic linker from the Advance
Toolchain release <var class="var">at</var> instead of the default versions that are
provided by the Linux distribution.  In general, this option is
intended for the developers of GCC, and it is not intended for general
use.
</p>
</dd>
<dt><code class="code">--enable-targets=all</code></dt>
<dt><code class="code">--enable-targets=<var class="var">target_list</var></code></dt>
<dd><p>Some GCC targets, e.g. powerpc64-linux, build bi-arch compilers.
These are compilers that are able to generate either 64-bit or 32-bit
code.  Typically, the corresponding 32-bit target, e.g.
powerpc-linux for powerpc64-linux, only generates 32-bit code.  This
option enables the 32-bit target to be a bi-arch compiler, which is
useful when you want a bi-arch compiler that defaults to 32-bit, and
you are building a bi-arch or multi-arch binutils in a combined tree.
On mips-linux, this will build a tri-arch compiler (ABI o32/n32/64),
defaulted to o32.
Currently, this option only affects sparc-linux, powerpc-linux, x86-linux,
mips-linux and s390-linux.
</p>
</dd>
<dt><code class="code">--enable-default-pie</code></dt>
<dd><p>Turn on <samp class="option">-fPIE</samp> and <samp class="option">-pie</samp> by default.
</p>
</dd>
<dt><code class="code">--enable-secureplt</code></dt>
<dd><p>This option enables <samp class="option">-msecure-plt</samp> by default for powerpc-linux.
See &ldquo;RS/6000 and PowerPC Options&rdquo; in the main manual
</p>
</dd>
<dt><code class="code">--enable-default-ssp</code></dt>
<dd><p>Turn on <samp class="option">-fstack-protector-strong</samp> by default.
</p>
</dd>
<dt><code class="code">--enable-cld</code></dt>
<dd><p>This option enables <samp class="option">-mcld</samp> by default for 32-bit x86 targets.
See &ldquo;i386 and x86-64 Options&rdquo; in the main manual
</p>
</dd>
<dt><code class="code">--enable-large-address-aware</code></dt>
<dd><p>The <samp class="option">--enable-large-address-aware</samp> option arranges for MinGW
executables to be linked using the <samp class="option">--large-address-aware</samp>
option, that enables the use of more than 2GB of memory.  If GCC is
configured with this option, its effects can be reversed by passing the
<samp class="option">-Wl,--disable-large-address-aware</samp> option to the so-configured
compiler driver.
</p>
</dd>
<dt><code class="code">--enable-win32-registry</code></dt>
<dt><code class="code">--enable-win32-registry=<var class="var">key</var></code></dt>
<dt><code class="code">--disable-win32-registry</code></dt>
<dd><p>The <samp class="option">--enable-win32-registry</samp> option enables Microsoft Windows-hosted GCC
to look up installations paths in the registry using the following key:
</p>
<div class="example smallexample">
<pre class="example-preformatted"><code class="code">HKEY_LOCAL_MACHINE\SOFTWARE\Free Software Foundation\<var class="var">key</var></code>
</pre></div>

<p><var class="var">key</var> defaults to GCC version number, and can be overridden by the
<samp class="option">--enable-win32-registry=<var class="var">key</var></samp> option.  Vendors and distributors
who use custom installers are encouraged to provide a different key,
perhaps one comprised of vendor name and GCC version number, to
avoid conflict with existing installations.  This feature is enabled
by default, and can be disabled by <samp class="option">--disable-win32-registry</samp>
option.  This option has no effect on the other hosts.
</p>
</dd>
<dt><code class="code">--nfp</code></dt>
<dd><p>Specify that the machine does not have a floating point unit.  This
option only applies to &lsquo;<samp class="samp">m68k-sun-sunos<var class="var">n</var></samp>&rsquo;.  On any other
system, <samp class="option">--nfp</samp> has no effect.
</p>
</dd>
<dt><code class="code">--enable-werror</code></dt>
<dt><code class="code">--disable-werror</code></dt>
<dt><code class="code">--enable-werror=yes</code></dt>
<dt><code class="code">--enable-werror=no</code></dt>
<dd><p>When you specify this option, it controls whether certain files in the
compiler are built with <samp class="option">-Werror</samp> in bootstrap stage2 and later.
If you don&rsquo;t specify it, <samp class="option">-Werror</samp> is turned on for the main
development trunk.  However it defaults to off for release branches and
final releases.  The specific files which get <samp class="option">-Werror</samp> are
controlled by the Makefiles.
</p>
</dd>
<dt><code class="code">--enable-checking</code></dt>
<dt><code class="code">--disable-checking</code></dt>
<dt><code class="code">--enable-checking=<var class="var">list</var></code></dt>
<dd><p>This option controls performing internal consistency checks in the compiler.
It does not change the generated code, but adds error checking of the
requested complexity.  This slows down the compiler and may only work
properly if you are building the compiler with GCC.
</p>
<p>When the option is not specified, the active set of checks depends on context.
Namely, bootstrap stage 1 defaults to &lsquo;<samp class="samp">--enable-checking=yes</samp>&rsquo;, builds
from release branches or release archives default to
&lsquo;<samp class="samp">--enable-checking=release</samp>&rsquo;, and otherwise
&lsquo;<samp class="samp">--enable-checking=yes,extra</samp>&rsquo; is used.  When the option is
specified without a <var class="var">list</var>, the result is the same as
&lsquo;<samp class="samp">--enable-checking=yes</samp>&rsquo;.  Likewise, &lsquo;<samp class="samp">--disable-checking</samp>&rsquo; is
equivalent to &lsquo;<samp class="samp">--enable-checking=no</samp>&rsquo;.
</p>
<p>The categories of checks available in <var class="var">list</var> are &lsquo;<samp class="samp">yes</samp>&rsquo; (most common
checks &lsquo;<samp class="samp">assert,misc,gc,gimple,rtlflag,runtime,tree,types</samp>&rsquo;), &lsquo;<samp class="samp">no</samp>&rsquo;
(no checks at all), &lsquo;<samp class="samp">all</samp>&rsquo; (all but &lsquo;<samp class="samp">valgrind</samp>&rsquo;), &lsquo;<samp class="samp">release</samp>&rsquo;
(cheapest checks &lsquo;<samp class="samp">assert,runtime</samp>&rsquo;) or &lsquo;<samp class="samp">none</samp>&rsquo; (same as &lsquo;<samp class="samp">no</samp>&rsquo;).
&lsquo;<samp class="samp">release</samp>&rsquo; checks are always on and to disable them
&lsquo;<samp class="samp">--disable-checking</samp>&rsquo; or &lsquo;<samp class="samp">--enable-checking=no[,&lt;other checks&gt;]</samp>&rsquo;
must be explicitly requested.  Disabling assertions makes the compiler and
runtime slightly faster but increases the risk of undetected internal errors
causing wrong code to be generated.
</p>
<p>Individual checks can be enabled with these flags: &lsquo;<samp class="samp">assert</samp>&rsquo;, &lsquo;<samp class="samp">df</samp>&rsquo;,
&lsquo;<samp class="samp">extra</samp>&rsquo;, &lsquo;<samp class="samp">fold</samp>&rsquo;, &lsquo;<samp class="samp">gc</samp>&rsquo;, &lsquo;<samp class="samp">gcac</samp>&rsquo;, &lsquo;<samp class="samp">gimple</samp>&rsquo;,
&lsquo;<samp class="samp">misc</samp>&rsquo;, &lsquo;<samp class="samp">rtl</samp>&rsquo;, &lsquo;<samp class="samp">rtlflag</samp>&rsquo;, &lsquo;<samp class="samp">runtime</samp>&rsquo;, &lsquo;<samp class="samp">tree</samp>&rsquo;,
&lsquo;<samp class="samp">types</samp>&rsquo; and &lsquo;<samp class="samp">valgrind</samp>&rsquo;.  &lsquo;<samp class="samp">extra</samp>&rsquo; extends &lsquo;<samp class="samp">misc</samp>&rsquo;
checking with extra checks that might affect code generation and should
therefore not differ between stage1 and later stages in bootstrap.
</p>
<p>The &lsquo;<samp class="samp">valgrind</samp>&rsquo; check requires the external <code class="command">valgrind</code> simulator,
available from <a class="uref" href="https://valgrind.org">https://valgrind.org</a>.  The &lsquo;<samp class="samp">rtl</samp>&rsquo; checks are
expensive and the &lsquo;<samp class="samp">df</samp>&rsquo;, &lsquo;<samp class="samp">gcac</samp>&rsquo; and &lsquo;<samp class="samp">valgrind</samp>&rsquo; checks are very
expensive.
</p>
</dd>
<dt><code class="code">--disable-stage1-checking</code></dt>
<dt><code class="code">--enable-stage1-checking</code></dt>
<dt><code class="code">--enable-stage1-checking=<var class="var">list</var></code></dt>
<dd><p>This option affects only bootstrap build.  If no <samp class="option">--enable-checking</samp>
option is specified the stage1 compiler is built with &lsquo;<samp class="samp">yes</samp>&rsquo; checking
enabled, otherwise the stage1 checking flags are the same as specified by
<samp class="option">--enable-checking</samp>.  To build the stage1 compiler with
different checking options use <samp class="option">--enable-stage1-checking</samp>.
The list of checking options is the same as for <samp class="option">--enable-checking</samp>.
If your system is too slow or too small to bootstrap a released compiler
with checking for stage1 enabled, you can use &lsquo;<samp class="samp">--disable-stage1-checking</samp>&rsquo;
to disable checking for the stage1 compiler.
</p>
</dd>
<dt><code class="code">--enable-coverage</code></dt>
<dt><code class="code">--enable-coverage=<var class="var">level</var></code></dt>
<dd><p>With this option, the compiler is built to collect self coverage
information, every time it is run.  This is for internal development
purposes, and only works when the compiler is being built with gcc.  The
<var class="var">level</var> argument controls whether the compiler is built optimized or
not, values are &lsquo;<samp class="samp">opt</samp>&rsquo; and &lsquo;<samp class="samp">noopt</samp>&rsquo;.  For coverage analysis you
want to disable optimization, for performance analysis you want to
enable optimization.  When coverage is enabled, the default level is
without optimization.
</p>
</dd>
<dt><code class="code">--enable-gather-detailed-mem-stats</code></dt>
<dd><p>When this option is specified more detailed information on memory
allocation is gathered.  This information is printed when using
<samp class="option">-fmem-report</samp>.
</p>
</dd>
<dt><code class="code">--enable-valgrind-annotations</code></dt>
<dd><p>Mark selected memory related operations in the compiler when run under
valgrind to suppress false positives.
</p>
</dd>
<dt><code class="code">--enable-nls</code></dt>
<dt><code class="code">--disable-nls</code></dt>
<dd><p>The <samp class="option">--enable-nls</samp> option enables Native Language Support (NLS),
which lets GCC output diagnostics in languages other than American
English.  Native Language Support is enabled by default if not doing a
canadian cross build.  The <samp class="option">--disable-nls</samp> option disables NLS.
</p>
</dd>
<dt><code class="code">--with-included-gettext</code></dt>
<dd><p>If NLS is enabled, the <samp class="option">--with-included-gettext</samp> option causes the build
procedure to prefer its copy of GNU <code class="command">gettext</code>.
</p>
</dd>
<dt><code class="code">--with-catgets</code></dt>
<dd><p>If NLS is enabled, and if the host lacks <code class="code">gettext</code> but has the
inferior <code class="code">catgets</code> interface, the GCC build procedure normally
ignores <code class="code">catgets</code> and instead uses GCC&rsquo;s copy of the GNU
<code class="code">gettext</code> library.  The <samp class="option">--with-catgets</samp> option causes the
build procedure to use the host&rsquo;s <code class="code">catgets</code> in this situation.
</p>
</dd>
<dt><code class="code">--with-libiconv-prefix=<var class="var">dir</var></code></dt>
<dd><p>Search for libiconv header files in <samp class="file"><var class="var">dir</var>/include</samp> and
libiconv library files in <samp class="file"><var class="var">dir</var>/lib</samp>.
</p>
</dd>
<dt><code class="code">--enable-obsolete</code></dt>
<dd><p>Enable configuration for an obsoleted system.  If you attempt to
configure GCC for a system (build, host, or target) which has been
obsoleted, and you do not specify this flag, configure will halt with an
error message.
</p>
<p>All support for systems which have been obsoleted in one release of GCC
is removed entirely in the next major release, unless someone steps
forward to maintain the port.
</p>
</dd>
<dt><code class="code">--enable-decimal-float</code></dt>
<dt><code class="code">--enable-decimal-float=yes</code></dt>
<dt><code class="code">--enable-decimal-float=no</code></dt>
<dt><code class="code">--enable-decimal-float=bid</code></dt>
<dt><code class="code">--enable-decimal-float=dpd</code></dt>
<dt><code class="code">--disable-decimal-float</code></dt>
<dd><p>Enable (or disable) support for the C decimal floating point extension
that is in the IEEE 754-2008 standard.  This is enabled by default
only on AArch64, PowerPC, i386, and x86_64 GNU/Linux systems.  Other
systems may also support it, but require the user to specifically
enable it.  You can optionally control which decimal floating point
format is used (either &lsquo;<samp class="samp">bid</samp>&rsquo; or &lsquo;<samp class="samp">dpd</samp>&rsquo;).  The &lsquo;<samp class="samp">bid</samp>&rsquo;
(binary integer decimal) format is default on AArch64, i386 and x86_64
systems, and the &lsquo;<samp class="samp">dpd</samp>&rsquo; (densely packed decimal) format is default
on PowerPC systems.
</p>
</dd>
<dt><code class="code">--enable-fixed-point</code></dt>
<dt><code class="code">--disable-fixed-point</code></dt>
<dd><p>Enable (or disable) support for C fixed-point arithmetic.
This option is enabled by default for some targets (such as MIPS) which
have hardware-support for fixed-point operations.  On other targets, you
may enable this option manually.
</p>
</dd>
<dt><code class="code">--with-long-double-128</code></dt>
<dd><p>Specify if <code class="code">long double</code> type should be 128-bit by default on selected
GNU/Linux architectures.  If using <code class="code">--without-long-double-128</code>,
<code class="code">long double</code> will be by default 64-bit, the same as <code class="code">double</code> type.
When neither of these configure options are used, the default will be
128-bit <code class="code">long double</code> when built against GNU C Library 2.4 and later,
64-bit <code class="code">long double</code> otherwise.
</p>
</dd>
<dt><code class="code">--with-long-double-format=ibm</code></dt>
<dt><code class="code">--with-long-double-format=ieee</code></dt>
<dd><p>Specify whether <code class="code">long double</code> uses the IBM extended double format
or the IEEE 128-bit floating point format on PowerPC Linux systems.
This configuration switch will only work on little endian PowerPC
Linux systems and on big endian 64-bit systems where the default cpu
is at least power7 (i.e. <samp class="option">--with-cpu=power7</samp>,
<samp class="option">--with-cpu=power8</samp>, or <samp class="option">--with-cpu=power9</samp> is used).
</p>
<p>If you use the <samp class="option">--with-long-double-64</samp> configuration option,
the <samp class="option">--with-long-double-format=ibm</samp> and
<samp class="option">--with-long-double-format=ieee</samp> options are ignored.
</p>
<p>The default <code class="code">long double</code> format is to use IBM extended double.
Until all of the libraries are converted to use IEEE 128-bit floating
point, it is not recommended to use
<samp class="option">--with-long-double-format=ieee</samp>.
</p>
</dd>
<dt><code class="code">--enable-fdpic</code></dt>
<dd><p>On SH Linux systems, generate ELF FDPIC code.
</p>
</dd>
<dt><code class="code">--with-gmp=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-gmp-include=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-gmp-lib=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-mpfr=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-mpfr-include=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-mpfr-lib=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-mpc=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-mpc-include=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-mpc-lib=<var class="var">pathname</var></code></dt>
<dd><p>If you want to build GCC but do not have the GMP library, the MPFR
library and/or the MPC library installed in a standard location and
do not have their sources present in the GCC source tree then you
can explicitly specify the directory where they are installed
(&lsquo;<samp class="samp">--with-gmp=<var class="var">gmpinstalldir</var></samp>&rsquo;,
&lsquo;<samp class="samp">--with-mpfr=<var class="var">mpfrinstalldir</var></samp>&rsquo;,
&lsquo;<samp class="samp">--with-mpc=<var class="var">mpcinstalldir</var></samp>&rsquo;).  The
<samp class="option">--with-gmp=<var class="var">gmpinstalldir</var></samp> option is shorthand for
<samp class="option">--with-gmp-lib=<var class="var">gmpinstalldir</var>/lib</samp> and
<samp class="option">--with-gmp-include=<var class="var">gmpinstalldir</var>/include</samp>.  Likewise the
<samp class="option">--with-mpfr=<var class="var">mpfrinstalldir</var></samp> option is shorthand for
<samp class="option">--with-mpfr-lib=<var class="var">mpfrinstalldir</var>/lib</samp> and
<samp class="option">--with-mpfr-include=<var class="var">mpfrinstalldir</var>/include</samp>, also the
<samp class="option">--with-mpc=<var class="var">mpcinstalldir</var></samp> option is shorthand for
<samp class="option">--with-mpc-lib=<var class="var">mpcinstalldir</var>/lib</samp> and
<samp class="option">--with-mpc-include=<var class="var">mpcinstalldir</var>/include</samp>.  If these
shorthand assumptions are not correct, you can use the explicit
include and lib options directly.  You might also need to ensure the
shared libraries can be found by the dynamic linker when building and
using GCC, for example by setting the runtime shared library path
variable (<code class="env">LD_LIBRARY_PATH</code> on GNU/Linux and Solaris systems).
</p>
<p>These flags are applicable to the host platform only.  When building
a cross compiler, they will not be used to configure target libraries.
</p>
</dd>
<dt><code class="code">--with-isl=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-isl-include=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-isl-lib=<var class="var">pathname</var></code></dt>
<dd><p>If you do not have the isl library installed in a standard location and you
want to build GCC, you can explicitly specify the directory where it is
installed (&lsquo;<samp class="samp">--with-isl=<var class="var">islinstalldir</var></samp>&rsquo;). The
<samp class="option">--with-isl=<var class="var">islinstalldir</var></samp> option is shorthand for
<samp class="option">--with-isl-lib=<var class="var">islinstalldir</var>/lib</samp> and
<samp class="option">--with-isl-include=<var class="var">islinstalldir</var>/include</samp>. If this
shorthand assumption is not correct, you can use the explicit
include and lib options directly.
</p>
<p>These flags are applicable to the host platform only.  When building
a cross compiler, they will not be used to configure target libraries.
</p>
</dd>
<dt><code class="code">--with-stage1-ldflags=<var class="var">flags</var></code></dt>
<dd><p>This option may be used to set linker flags to be used when linking
stage 1 of GCC.  These are also used when linking GCC if configured with
<samp class="option">--disable-bootstrap</samp>.  If <samp class="option">--with-stage1-libs</samp> is not set to a
value, then the default is &lsquo;<samp class="samp">-static-libstdc++ -static-libgcc</samp>&rsquo;, if
supported.
</p>
</dd>
<dt><code class="code">--with-stage1-libs=<var class="var">libs</var></code></dt>
<dd><p>This option may be used to set libraries to be used when linking stage 1
of GCC.  These are also used when linking GCC if configured with
<samp class="option">--disable-bootstrap</samp>.
</p>
</dd>
<dt><code class="code">--with-boot-ldflags=<var class="var">flags</var></code></dt>
<dd><p>This option may be used to set linker flags to be used when linking
stage 2 and later when bootstrapping GCC.  If &ndash;with-boot-libs
is not is set to a value, then the default is
&lsquo;<samp class="samp">-static-libstdc++ -static-libgcc</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">--with-boot-libs=<var class="var">libs</var></code></dt>
<dd><p>This option may be used to set libraries to be used when linking stage 2
and later when bootstrapping GCC.
</p>
</dd>
<dt><code class="code">--with-debug-prefix-map=<var class="var">map</var></code></dt>
<dd><p>Convert source directory names using <samp class="option">-fdebug-prefix-map</samp> when
building runtime libraries.  &lsquo;<samp class="samp"><var class="var">map</var></samp>&rsquo; is a space-separated
list of maps of the form &lsquo;<samp class="samp"><var class="var">old</var>=<var class="var">new</var></samp>&rsquo;.
</p>
</dd>
<dt><code class="code">--enable-linker-build-id</code></dt>
<dd><p>Tells GCC to pass <samp class="option">--build-id</samp> option to the linker for all final
links (links performed without the <samp class="option">-r</samp> or <samp class="option">--relocatable</samp>
option), if the linker supports it.  If you specify
<samp class="option">--enable-linker-build-id</samp>, but your linker does not
support <samp class="option">--build-id</samp> option, a warning is issued and the
<samp class="option">--enable-linker-build-id</samp> option is ignored.  The default is off.
</p>
</dd>
<dt><code class="code">--with-linker-hash-style=<var class="var">choice</var></code></dt>
<dd><p>Tells GCC to pass <samp class="option">--hash-style=<var class="var">choice</var></samp> option to the
linker for all final links. <var class="var">choice</var> can be one of
&lsquo;<samp class="samp">sysv</samp>&rsquo;, &lsquo;<samp class="samp">gnu</samp>&rsquo;, and &lsquo;<samp class="samp">both</samp>&rsquo; where &lsquo;<samp class="samp">sysv</samp>&rsquo; is the default.
</p>
</dd>
<dt><code class="code">--enable-gnu-unique-object</code></dt>
<dt><code class="code">--disable-gnu-unique-object</code></dt>
<dd><p>Tells GCC to use the gnu_unique_object relocation for C++ template
static data members and inline function local statics.  Enabled by
default for a toolchain with an assembler that accepts it and
GLIBC 2.11 or above, otherwise disabled.
</p>
</dd>
<dt><code class="code">--with-diagnostics-color=<var class="var">choice</var></code></dt>
<dd><p>Tells GCC to use <var class="var">choice</var> as the default for <samp class="option">-fdiagnostics-color=</samp>
option (if not used explicitly on the command line).  <var class="var">choice</var>
can be one of &lsquo;<samp class="samp">never</samp>&rsquo;, &lsquo;<samp class="samp">auto</samp>&rsquo;, &lsquo;<samp class="samp">always</samp>&rsquo;, and &lsquo;<samp class="samp">auto-if-env</samp>&rsquo;
where &lsquo;<samp class="samp">auto</samp>&rsquo; is the default.  &lsquo;<samp class="samp">auto-if-env</samp>&rsquo; makes
<samp class="option">-fdiagnostics-color=auto</samp> the default if <code class="env">GCC_COLORS</code>
is present and non-empty in the environment of the compiler, and
<samp class="option">-fdiagnostics-color=never</samp> otherwise.
</p>
</dd>
<dt><code class="code">--with-diagnostics-urls=<var class="var">choice</var></code></dt>
<dd><p>Tells GCC to use <var class="var">choice</var> as the default for <samp class="option">-fdiagnostics-urls=</samp>
option (if not used explicitly on the command line).  <var class="var">choice</var>
can be one of &lsquo;<samp class="samp">never</samp>&rsquo;, &lsquo;<samp class="samp">auto</samp>&rsquo;, &lsquo;<samp class="samp">always</samp>&rsquo;, and &lsquo;<samp class="samp">auto-if-env</samp>&rsquo;
where &lsquo;<samp class="samp">auto</samp>&rsquo; is the default.  &lsquo;<samp class="samp">auto-if-env</samp>&rsquo; makes
<samp class="option">-fdiagnostics-urls=auto</samp> the default if <code class="env">GCC_URLS</code>
or <code class="env">TERM_URLS</code> is present and non-empty in the environment of the
compiler, and <samp class="option">-fdiagnostics-urls=never</samp> otherwise.
</p>
</dd>
<dt><code class="code">--enable-lto</code></dt>
<dt><code class="code">--disable-lto</code></dt>
<dd><p>Enable support for link-time optimization (LTO).  This is enabled by
default, and may be disabled using <samp class="option">--disable-lto</samp>.
</p>
</dd>
<dt><code class="code">--enable-linker-plugin-configure-flags=FLAGS</code></dt>
<dt><code class="code">--enable-linker-plugin-flags=FLAGS</code></dt>
<dd><p>By default, linker plugins (such as the LTO plugin) are built for the
host system architecture.  For the case that the linker has a
different (but run-time compatible) architecture, these flags can be
specified to build plugins that are compatible to the linker.  For
example, if you are building GCC for a 64-bit x86_64
(&lsquo;<samp class="samp">x86_64-pc-linux-gnu</samp>&rsquo;) host system, but have a 32-bit x86
GNU/Linux (&lsquo;<samp class="samp">i686-pc-linux-gnu</samp>&rsquo;) linker executable (which is
executable on the former system), you can configure GCC as follows for
getting compatible linker plugins:
</p>
<div class="example smallexample">
<pre class="example-preformatted">% <var class="var">srcdir</var>/configure \
    --host=x86_64-pc-linux-gnu \
    --enable-linker-plugin-configure-flags=--host=i686-pc-linux-gnu \
    --enable-linker-plugin-flags='CC=gcc\ -m32\ -Wl,-rpath,[...]/i686-pc-linux-gnu/lib'
</pre></div>

</dd>
<dt><code class="code">--with-plugin-ld=<var class="var">pathname</var></code></dt>
<dd><p>Enable an alternate linker to be used at link-time optimization (LTO)
link time when <samp class="option">-fuse-linker-plugin</samp> is enabled.
This linker should have plugin support such as gold starting with
version 2.20 or GNU ld starting with version 2.21.
See <samp class="option">-fuse-linker-plugin</samp> for details.
</p>
</dd>
<dt><code class="code">--enable-canonical-system-headers</code></dt>
<dt><code class="code">--disable-canonical-system-headers</code></dt>
<dd><p>Enable system header path canonicalization for <samp class="file">libcpp</samp>.  This can
produce shorter header file paths in diagnostics and dependency output
files, but these changed header paths may conflict with some compilation
environments.  Enabled by default, and may be disabled using
<samp class="option">--disable-canonical-system-headers</samp>.
</p>
</dd>
<dt><code class="code">--with-glibc-version=<var class="var">major</var>.<var class="var">minor</var></code></dt>
<dd><p>Tell GCC that when the GNU C Library (glibc) is used on the target it
will be version <var class="var">major</var>.<var class="var">minor</var> or later.  Normally this can
be detected from the C library&rsquo;s header files, but this option may be
needed when bootstrapping a cross toolchain without the header files
available for building the initial bootstrap compiler.
</p>
<p>If GCC is configured with some multilibs that use glibc and some that
do not, this option applies only to the multilibs that use glibc.
However, such configurations may not work well as not all the relevant
configuration in GCC is on a per-multilib basis.
</p>
</dd>
<dt><code class="code">--enable-as-accelerator-for=<var class="var">target</var></code></dt>
<dd><p>Build as offload target compiler. Specify offload host triple by <var class="var">target</var>.
</p>
</dd>
<dt><code class="code">--enable-offload-targets=<var class="var">target1</var>[=<var class="var">path1</var>],&hellip;,<var class="var">targetN</var>[=<var class="var">pathN</var>]</code></dt>
<dd><p>Enable offloading to targets <var class="var">target1</var>, &hellip;, <var class="var">targetN</var>.
Offload compilers are expected to be already installed.  Default search
path for them is <samp class="file"><var class="var">exec-prefix</var></samp>, but it can be changed by
specifying paths <var class="var">path1</var>, &hellip;, <var class="var">pathN</var>.
</p>
<div class="example smallexample">
<pre class="example-preformatted">% <var class="var">srcdir</var>/configure \
    --enable-offload-targets=amdgcn-amdhsa,nvptx-none
</pre></div>

</dd>
<dt><code class="code">--enable-offload-defaulted</code></dt>
<dd>
<p>Tell GCC that configured but not installed offload compilers and libgomp
plugins are silently ignored.  Useful for distribution compilers where
those are in separate optional packages and where the presence or absence
of those optional packages should determine the actual supported offloading
target set rather than the GCC configure-time selection.
</p>
</dd>
<dt><code class="code">--enable-cet</code></dt>
<dt><code class="code">--disable-cet</code></dt>
<dd><p>Enable building target run-time libraries with control-flow
instrumentation, see <samp class="option">-fcf-protection</samp> option.  When
<code class="code">--enable-cet</code> is specified target libraries are configured
to add <samp class="option">-fcf-protection</samp> and, if needed, other target
specific options to a set of building options.
</p>
<p><code class="code">--enable-cet=auto</code> is default.  CET is enabled on Linux/x86 if
target binutils supports <code class="code">Intel CET</code> instructions and disabled
otherwise.  In this case, the target libraries are configured to get
additional <samp class="option">-fcf-protection</samp> option.
</p>
</dd>
<dt><code class="code">--with-riscv-attribute=&lsquo;<samp class="samp">yes</samp>&rsquo;, &lsquo;<samp class="samp">no</samp>&rsquo; or &lsquo;<samp class="samp">default</samp>&rsquo;</code></dt>
<dd><p>Generate RISC-V attribute by default, in order to record extra build
information in object.
</p>
<p>The option is disabled by default. It is enabled on RISC-V/ELF (bare-metal)
target if target binutils supported.
</p>
</dd>
<dt><code class="code">--enable-s390-excess-float-precision</code></dt>
<dt><code class="code">--disable-s390-excess-float-precision</code></dt>
<dd><p>On s390(x) targets, enable treatment of float expressions with double precision
when in standards-compliant mode (e.g., when <code class="code">--std=c99</code> or
<code class="code">-fexcess-precision=standard</code> are given).
</p>
<p>For a native build and cross compiles that have target headers, the option&rsquo;s
default is derived from glibc&rsquo;s behavior. When glibc clamps float_t to double,
GCC follows and enables the option. For other cross compiles, the default is
disabled.
</p>
</dd>
<dt><code class="code">--with-zstd=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-zstd-include=<var class="var">pathname</var></code></dt>
<dt><code class="code">--with-zstd-lib=<var class="var">pathname</var></code></dt>
<dd><p>If you do not have the <code class="code">zstd</code> library installed in a standard
location and you want to build GCC, you can explicitly specify the
directory where it is installed (&lsquo;<samp class="samp">--with-zstd=<var class="var">zstdinstalldir</var></samp>&rsquo;).
The <samp class="option">--with-zstd=<var class="var">zstdinstalldir</var></samp> option is shorthand for
<samp class="option">--with-zstd-lib=<var class="var">zstdinstalldir</var>/lib</samp> and
<samp class="option">--with-zstd-include=<var class="var">zstdinstalldir</var>/include</samp>. If this
shorthand assumption is not correct, you can use the explicit
include and lib options directly.
</p>
<p>These flags are applicable to the host platform only.  When building
a cross compiler, they will not be used to configure target libraries.
</p></dd>
</dl>

<h4 class="subheading" id="Cross-Compiler-Specific-Options"><span>Cross-Compiler-Specific Options<a class="copiable-link" href="#Cross-Compiler-Specific-Options"> &para;</a></span></h4>
<p>The following options only apply to building cross compilers.
</p>
<dl class="table">
<dt><code class="code">--with-toolexeclibdir=<var class="var">dir</var></code></dt>
<dd><p>Specify the installation directory for libraries built with a cross compiler.
The default is <samp class="option">${gcc_tooldir}/lib</samp>.
</p>
</dd>
<dt><code class="code">--with-sysroot</code></dt>
<dt><code class="code">--with-sysroot=<var class="var">dir</var></code></dt>
<dd><p>Tells GCC to consider <var class="var">dir</var> as the root of a tree that contains
(a subset of) the root filesystem of the target operating system.
Target system headers, libraries and run-time object files will be
searched for in there.  More specifically, this acts as if
<samp class="option">--sysroot=<var class="var">dir</var></samp> was added to the default options of the built
compiler.  The specified directory is not copied into the
install tree, unlike the options <samp class="option">--with-headers</samp> and
<samp class="option">--with-libs</samp> that this option obsoletes.  The default value,
in case <samp class="option">--with-sysroot</samp> is not given an argument, is
<samp class="option">${gcc_tooldir}/sys-root</samp>.  If the specified directory is a
subdirectory of <samp class="option">${exec_prefix}</samp>, then it will be found relative to
the GCC binaries if the installation tree is moved.
</p>
<p>This option affects the system root for the compiler used to build
target libraries (which runs on the build system) and the compiler newly
installed with <code class="code">make install</code>; it does not affect the compiler which is
used to build GCC itself.
</p>
<p>If you specify the <samp class="option">--with-native-system-header-dir=<var class="var">dirname</var></samp>
option then the compiler will search that directory within <var class="var">dirname</var> for
native system headers rather than the default <samp class="file">/usr/include</samp>.
</p>
</dd>
<dt><code class="code">--with-build-sysroot</code></dt>
<dt><code class="code">--with-build-sysroot=<var class="var">dir</var></code></dt>
<dd><p>Tells GCC to consider <var class="var">dir</var> as the system root (see
<samp class="option">--with-sysroot</samp>) while building target libraries, instead of
the directory specified with <samp class="option">--with-sysroot</samp>.  This option is
only useful when you are already using <samp class="option">--with-sysroot</samp>.  You
can use <samp class="option">--with-build-sysroot</samp> when you are configuring with
<samp class="option">--prefix</samp> set to a directory that is different from the one in
which you are installing GCC and your target libraries.
</p>
<p>This option affects the system root for the compiler used to build
target libraries (which runs on the build system); it does not affect
the compiler which is used to build GCC itself.
</p>
<p>If you specify the <samp class="option">--with-native-system-header-dir=<var class="var">dirname</var></samp>
option then the compiler will search that directory within <var class="var">dirname</var> for
native system headers rather than the default <samp class="file">/usr/include</samp>.
</p>
</dd>
<dt><code class="code">--with-headers</code></dt>
<dt><code class="code">--with-headers=<var class="var">dir</var></code></dt>
<dd><p>Deprecated in favor of <samp class="option">--with-sysroot</samp>.
Specifies that target headers are available when building a cross compiler.
The <var class="var">dir</var> argument specifies a directory which has the target include
files.  These include files will be copied into the <samp class="file">gcc</samp> install
directory.  <em class="emph">This option with the <var class="var">dir</var> argument is required</em> when
building a cross compiler, if <samp class="file"><var class="var">prefix</var>/<var class="var">target</var>/sys-include</samp>
doesn&rsquo;t pre-exist.  If <samp class="file"><var class="var">prefix</var>/<var class="var">target</var>/sys-include</samp> does
pre-exist, the <var class="var">dir</var> argument may be omitted.  <code class="command">fixincludes</code>
will be run on these files to make them compatible with GCC.
</p>
</dd>
<dt><code class="code">--without-headers</code></dt>
<dd><p>Tells GCC not use any target headers from a libc when building a cross
compiler.  When crossing to GNU/Linux, you need the headers so GCC
can build the exception handling for libgcc.
</p>
</dd>
<dt><code class="code">--with-libs</code></dt>
<dt><code class="code">--with-libs=&quot;<var class="var">dir1</var> <var class="var">dir2</var> &hellip; <var class="var">dirN</var>&quot;</code></dt>
<dd><p>Deprecated in favor of <samp class="option">--with-sysroot</samp>.
Specifies a list of directories which contain the target runtime
libraries.  These libraries will be copied into the <samp class="file">gcc</samp> install
directory.  If the directory list is omitted, this option has no
effect.
</p>
</dd>
<dt><code class="code">--with-newlib</code></dt>
<dd><p>Specifies that &lsquo;<samp class="samp">newlib</samp>&rsquo; is
being used as the target C library.  This causes <code class="code">__eprintf</code> to be
omitted from <samp class="file">libgcc.a</samp> on the assumption that it will be provided by
&lsquo;<samp class="samp">newlib</samp>&rsquo;.
</p>
<a name="avr"></a>
</dd>
<dt><code class="code">--with-avrlibc</code></dt>
<dd><p>Only supported for the AVR target. Specifies that &lsquo;<samp class="samp">AVR-Libc</samp>&rsquo; is
being used as the target C&nbsp; library.  This causes float support
functions like <code class="code">__addsf3</code> to be omitted from <samp class="file">libgcc.a</samp> on
the assumption that it will be provided by <samp class="file">libm.a</samp>.  For more
technical details, cf. <a class="uref" href="https://gcc.gnu.org/PR54461">PR54461</a>.
It is not supported for
RTEMS configurations, which currently use newlib.  The option is
supported since version 4.7.2 and is the default in 4.8.0 and newer.
</p>
</dd>
<dt><code class="code">--with-double={32|64|32,64|64,32}</code></dt>
<dt><code class="code">--with-long-double={32|64|32,64|64,32|double}</code></dt>
<dd><p>Only supported for the AVR target since version&nbsp;10.
Specify the default layout available for the C/C++ &lsquo;<samp class="samp">double</samp>&rsquo;
and &lsquo;<samp class="samp">long double</samp>&rsquo; type, respectively. The following rules apply:
</p><ul class="itemize mark-bullet">
<li>The first value after the &lsquo;<samp class="samp">=</samp>&rsquo; specifies the default layout (in bits)
of the type and also the default for the <samp class="option">-mdouble=</samp> resp.
<samp class="option">-mlong-double=</samp> compiler option.
</li><li>If more than one value is specified, respective multilib variants are
available, and  <samp class="option">-mdouble=</samp> resp. <samp class="option">-mlong-double=</samp> acts
as a multilib option.
</li><li>If <samp class="option">--with-long-double=double</samp> is specified, &lsquo;<samp class="samp">double</samp>&rsquo; and
&lsquo;<samp class="samp">long double</samp>&rsquo; will have the same layout.
</li><li>The defaults are <samp class="option">--with-long-double=64,32</samp> and
<samp class="option">--with-double=32,64</samp>.  The default &lsquo;<samp class="samp">double</samp>&rsquo; layout imposed by
the latter is compatible with older versions of the compiler that implement
&lsquo;<samp class="samp">double</samp>&rsquo; as a 32-bit type, which does not comply to the language standard.
</li></ul>
<p>Not all combinations of <samp class="option">--with-double=</samp> and
<samp class="option">--with-long-double=</samp> are valid.  For example, the combination
<samp class="option">--with-double=32,64</samp> <samp class="option">--with-long-double=32</samp> will be
rejected because the first option specifies the availability of
multilibs for &lsquo;<samp class="samp">double</samp>&rsquo;, whereas the second option implies
that &lsquo;<samp class="samp">long double</samp>&rsquo; &mdash; and hence also &lsquo;<samp class="samp">double</samp>&rsquo; &mdash; is always
32&nbsp;bits wide.
</p>
</dd>
<dt><code class="code">--with-double-comparison={tristate|bool|libf7}</code></dt>
<dd><p>Only supported for the AVR target since version&nbsp;10.
Specify what result format is returned by library functions that
compare 64-bit floating point values (<code class="code">DFmode</code>).
The GCC default is &lsquo;<samp class="samp">tristate</samp>&rsquo;.  If the floating point
implementation returns a boolean instead, set it to &lsquo;<samp class="samp">bool</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">--with-libf7={libgcc|math|math-symbols|no}</code></dt>
<dd><p>Only supported for the AVR target since version&nbsp;10.
Specify to which degree code from LibF7 is included in libgcc.
LibF7 is an ad-hoc, AVR-specific, 64-bit floating point emulation
written in C and (inline) assembly. &lsquo;<samp class="samp">libgcc</samp>&rsquo; adds support
for functions that one would usually expect in libgcc like double addition,
double comparisons and double conversions. &lsquo;<samp class="samp">math</samp>&rsquo; also adds routines
that one would expect in <samp class="file">libm.a</samp>, but with <code class="code">__</code> (two underscores)
prepended to the symbol names as specified by <samp class="file">math.h</samp>.
&lsquo;<samp class="samp">math-symbols</samp>&rsquo; also defines weak aliases for the functions
declared in <samp class="file">math.h</samp>.  However, <code class="code">--with-libf7</code> won&rsquo;t
install no <samp class="file">math.h</samp> header file whatsoever, this file must come
from elsewhere.  This option sets <samp class="option">--with-double-comparison</samp>
to &lsquo;<samp class="samp">bool</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">--with-nds32-lib=<var class="var">library</var></code></dt>
<dd><p>Specifies that <var class="var">library</var> setting is used for building <samp class="file">libgcc.a</samp>.
Currently, the valid <var class="var">library</var> is &lsquo;<samp class="samp">newlib</samp>&rsquo; or &lsquo;<samp class="samp">mculib</samp>&rsquo;.
This option is only supported for the NDS32 target.
</p>
</dd>
<dt><code class="code">--with-build-time-tools=<var class="var">dir</var></code></dt>
<dd><p>Specifies where to find the set of target tools (assembler, linker, etc.)
that will be used while building GCC itself.  This option can be useful
if the directory layouts are different between the system you are building
GCC on, and the system where you will deploy it.
</p>
<p>For example, on an &lsquo;<samp class="samp">ia64-hp-hpux</samp>&rsquo; system, you may have the GNU
assembler and linker in <samp class="file">/usr/bin</samp>, and the native tools in a
different path, and build a toolchain that expects to find the
native tools in <samp class="file">/usr/bin</samp>.
</p>
<p>When you use this option, you should ensure that <var class="var">dir</var> includes
<code class="command">ar</code>, <code class="command">as</code>, <code class="command">ld</code>, <code class="command">nm</code>,
<code class="command">ranlib</code> and <code class="command">strip</code> if necessary, and possibly
<code class="command">objdump</code>.  Otherwise, GCC may use an inconsistent set of
tools.
</p></dd>
</dl>

<h4 class="subsubheading" id="Overriding-configure-test-results"><span>Overriding <code class="command">configure</code> test results<a class="copiable-link" href="#Overriding-configure-test-results"> &para;</a></span></h4>

<p>Sometimes, it might be necessary to override the result of some
<code class="command">configure</code> test, for example in order to ease porting to a new
system or work around a bug in a test.  The toplevel <code class="command">configure</code>
script provides three variables for this:
</p>
<dl class="table">
<dt><a id="index-build_005fconfigargs"></a><span><code class="code">build_configargs</code><a class="copiable-link" href="#index-build_005fconfigargs"> &para;</a></span></dt>
<dd><p>The contents of this variable is passed to all build <code class="command">configure</code>
scripts.
</p>
</dd>
<dt><a id="index-host_005fconfigargs"></a><span><code class="code">host_configargs</code><a class="copiable-link" href="#index-host_005fconfigargs"> &para;</a></span></dt>
<dd><p>The contents of this variable is passed to all host <code class="command">configure</code>
scripts.
</p>
</dd>
<dt><a id="index-target_005fconfigargs"></a><span><code class="code">target_configargs</code><a class="copiable-link" href="#index-target_005fconfigargs"> &para;</a></span></dt>
<dd><p>The contents of this variable is passed to all target <code class="command">configure</code>
scripts.
</p>
</dd>
</dl>

<p>In order to avoid shell and <code class="command">make</code> quoting issues for complex
overrides, you can pass a setting for <code class="env">CONFIG_SITE</code> and set
variables in the site file.
</p>
<h4 class="subheading" id="Objective-C-Specific-Options"><span>Objective-C-Specific Options<a class="copiable-link" href="#Objective-C-Specific-Options"> &para;</a></span></h4>

<p>The following options apply to the build of the Objective-C runtime library.
</p>
<dl class="table">
<dt><code class="code">--enable-objc-gc</code></dt>
<dd><p>Specify that an additional variant of the GNU Objective-C runtime library
is built, using an external build of the Boehm-Demers-Weiser garbage
collector (<a class="uref" href="https://www.hboehm.info/gc/">https://www.hboehm.info/gc/</a>).  This library needs to be
available for each multilib variant, unless configured with
<samp class="option">--enable-objc-gc=&lsquo;<samp class="samp">auto</samp>&rsquo;</samp> in which case the build of the
additional runtime library is skipped when not available and the build
continues.
</p>
</dd>
<dt><code class="code">--with-target-bdw-gc=<var class="var">list</var></code></dt>
<dt><code class="code">--with-target-bdw-gc-include=<var class="var">list</var></code></dt>
<dt><code class="code">--with-target-bdw-gc-lib=<var class="var">list</var></code></dt>
<dd><p>Specify search directories for the garbage collector header files and
libraries. <var class="var">list</var> is a comma separated list of key value pairs of the
form &lsquo;<samp class="samp"><var class="var">multilibdir</var>=<var class="var">path</var></samp>&rsquo;, where the default multilib key
is named as &lsquo;<samp class="samp">.</samp>&rsquo; (dot), or is omitted (e.g.
&lsquo;<samp class="samp">--with-target-bdw-gc=/opt/bdw-gc,32=/opt-bdw-gc32</samp>&rsquo;).
</p>
<p>The options <samp class="option">--with-target-bdw-gc-include</samp> and
<samp class="option">--with-target-bdw-gc-lib</samp> must always be specified together
for each multilib variant and they take precedence over
<samp class="option">--with-target-bdw-gc</samp>.  If <samp class="option">--with-target-bdw-gc-include</samp>
is missing values for a multilib, then the value for the default
multilib is used (e.g. &lsquo;<samp class="samp">--with-target-bdw-gc-include=/opt/bdw-gc/include</samp>&rsquo;
&lsquo;<samp class="samp">--with-target-bdw-gc-lib=/opt/bdw-gc/lib64,32=/opt-bdw-gc/lib32</samp>&rsquo;).
If none of these options are specified, the library is assumed in
default locations.
</p></dd>
</dl>

<h4 class="subheading" id="D-Specific-Options"><span>D-Specific Options<a class="copiable-link" href="#D-Specific-Options"> &para;</a></span></h4>

<p>The following options apply to the build of the D runtime library.
</p>
<dl class="table">
<dt><code class="code">--enable-libphobos-checking</code></dt>
<dt><code class="code">--disable-libphobos-checking</code></dt>
<dt><code class="code">--enable-libphobos-checking=<var class="var">list</var></code></dt>
<dd><p>This option controls whether run-time checks and contracts are compiled into
the D runtime library.  When the option is not specified, the library is built
with &lsquo;<samp class="samp">release</samp>&rsquo; checking.  When the option is specified without a
<var class="var">list</var>, the result is the same as &lsquo;<samp class="samp">--enable-libphobos-checking=yes</samp>&rsquo;.
Likewise, &lsquo;<samp class="samp">--disable-libphobos-checking</samp>&rsquo; is equivalent to
&lsquo;<samp class="samp">--enable-libphobos-checking=no</samp>&rsquo;.
</p>
<p>The categories of checks available in <var class="var">list</var> are &lsquo;<samp class="samp">yes</samp>&rsquo; (compiles
libphobos with <samp class="option">-fno-release</samp>), &lsquo;<samp class="samp">no</samp>&rsquo; (compiles libphobos with
<samp class="option">-frelease</samp>), &lsquo;<samp class="samp">all</samp>&rsquo; (same as &lsquo;<samp class="samp">yes</samp>&rsquo;), &lsquo;<samp class="samp">none</samp>&rsquo; or
&lsquo;<samp class="samp">release</samp>&rsquo; (same as &lsquo;<samp class="samp">no</samp>&rsquo;).
</p>
<p>Individual checks available in <var class="var">list</var> are &lsquo;<samp class="samp">assert</samp>&rsquo; (compiles libphobos
with an extra option <samp class="option">-fassert</samp>).
</p>
</dd>
<dt><code class="code">--with-libphobos-druntime-only</code></dt>
<dt><code class="code">--with-libphobos-druntime-only=<var class="var">choice</var></code></dt>
<dd><p>Specify whether to build only the core D runtime library (druntime), or both
the core and standard library (phobos) into libphobos.  This is useful for
targets that have full support in druntime, but no or incomplete support
in phobos.  <var class="var">choice</var> can be one of &lsquo;<samp class="samp">auto</samp>&rsquo;, &lsquo;<samp class="samp">yes</samp>&rsquo;, and &lsquo;<samp class="samp">no</samp>&rsquo;
where &lsquo;<samp class="samp">auto</samp>&rsquo; is the default.
</p>
<p>When the option is not specified, the default choice &lsquo;<samp class="samp">auto</samp>&rsquo; means that it
is inferred whether the target has support for the phobos standard library.
When the option is specified without a <var class="var">choice</var>,  the result is the same as
&lsquo;<samp class="samp">--with-libphobos-druntime-only=yes</samp>&rsquo;.
</p>
</dd>
<dt><code class="code">--with-target-system-zlib</code></dt>
<dd><p>Use installed &lsquo;<samp class="samp">zlib</samp>&rsquo; rather than that included with GCC.  This needs
to be available for each multilib variant, unless configured with
<samp class="option">--with-target-system-zlib=&lsquo;<samp class="samp">auto</samp>&rsquo;</samp> in which case the GCC&nbsp;included
&lsquo;<samp class="samp">zlib</samp>&rsquo; is only used when the system installed library is not available.
</p></dd>
</dl>

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<p>
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